Hello, In some documentation I was reading last night about laying out OSDs, it was suggested that if more that one OSD uses the same NVMe drive, the failure-domain should probably be set to node. However, for a small cluster the inclination is to use EC-pools and failure-domain = OSD. I was wondering if there is a middle ground - could we define failure-domain = NVMe? I think the map would need to be defined manually in the same way that failure-domain = rack requires information about which nodes are in each rack. Example: My latest OSD nodes have 8 HDDs and 3 U.2 NVMe. I'd set up the WAL/DB for with HDDs per OSD (wasted space on the 3rd NVMe). Across all my OSD nodes I will have 8 HDDs and either 2 or 3 NVMe devices per node - 15 total NVMe devices. My preferred EC-pool profile is 8+2. It seems that this profile could be safely dispersed across 15 failure domains, resulting in protection against NVMe failure. Please let me know if this is worth pursuing. Thanks. -Dave -- Dave Hall Binghamton University kdhall@binghamton.edu 607-760-2328 (Cell) 607-777-4641 (Office)
Don't forget if you have server failure you might loose many objects. If the failure domain is osd, it means let's say you have 12 drives in each server, 8+2 EC in an unlucky situation can be located in 1 server also. Istvan Szabo Senior Infrastructure Engineer --------------------------------------------------- Agoda Services Co., Ltd. e: istvan.szabo@agoda.com --------------------------------------------------- -----Original Message----- From: Dave Hall <kdhall@binghamton.edu> Sent: Wednesday, March 10, 2021 11:42 PM To: ceph-users <ceph-users@ceph.io> Subject: [ceph-users] Failure Domain = NVMe? Email received from outside the company. If in doubt don't click links nor open attachments! ________________________________ Hello, In some documentation I was reading last night about laying out OSDs, it was suggested that if more that one OSD uses the same NVMe drive, the failure-domain should probably be set to node. However, for a small cluster the inclination is to use EC-pools and failure-domain = OSD. I was wondering if there is a middle ground - could we define failure-domain = NVMe? I think the map would need to be defined manually in the same way that failure-domain = rack requires information about which nodes are in each rack. Example: My latest OSD nodes have 8 HDDs and 3 U.2 NVMe. I'd set up the WAL/DB for with HDDs per OSD (wasted space on the 3rd NVMe). Across all my OSD nodes I will have 8 HDDs and either 2 or 3 NVMe devices per node - 15 total NVMe devices. My preferred EC-pool profile is 8+2. It seems that this profile could be safely dispersed across 15 failure domains, resulting in protection against NVMe failure. Please let me know if this is worth pursuing. Thanks. -Dave -- Dave Hall Binghamton University kdhall@binghamton.edu 607-760-2328 (Cell) 607-777-4641 (Office) _______________________________________________ ceph-users mailing list -- ceph-users@ceph.io To unsubscribe send an email to ceph-users-leave@ceph.io ________________________________ This message is confidential and is for the sole use of the intended recipient(s). It may also be privileged or otherwise protected by copyright or other legal rules. If you have received it by mistake please let us know by reply email and delete it from your system. It is prohibited to copy this message or disclose its content to anyone. Any confidentiality or privilege is not waived or lost by any mistaken delivery or unauthorized disclosure of the message. All messages sent to and from Agoda may be monitored to ensure compliance with company policies, to protect the company's interests and to remove potential malware. Electronic messages may be intercepted, amended, lost or deleted, or contain viruses.
Istvan, I agree that there is always risk with failure-domain < node, especially with EC pools. We are accepting this risk to lower the financial barrier to entry. In our minds, we have good power protection and new hardware, so the greatest immediate risks for our smaller cluster (approaching 6 OSD nodes and 48 HDDs) are NVMe write exhaustion and HDD failures. Since we have multiple OSDs sharing a single NVMe device it occurs to me that we might want to get Ceph to 'map' against that. In a way, NVMe devices are our 'nodes' at the current size of our cluster. -Dave -- Dave Hall Binghamton University On Wed, Mar 10, 2021 at 10:41 PM Szabo, Istvan (Agoda) < Istvan.Szabo@agoda.com> wrote:
Don't forget if you have server failure you might loose many objects. If the failure domain is osd, it means let's say you have 12 drives in each server, 8+2 EC in an unlucky situation can be located in 1 server also.
Istvan Szabo Senior Infrastructure Engineer --------------------------------------------------- Agoda Services Co., Ltd. e: istvan.szabo@agoda.com ---------------------------------------------------
-----Original Message----- From: Dave Hall <kdhall@binghamton.edu> Sent: Wednesday, March 10, 2021 11:42 PM To: ceph-users <ceph-users@ceph.io> Subject: [ceph-users] Failure Domain = NVMe?
Email received from outside the company. If in doubt don't click links nor open attachments! ________________________________
Hello,
In some documentation I was reading last night about laying out OSDs, it was suggested that if more that one OSD uses the same NVMe drive, the failure-domain should probably be set to node. However, for a small cluster the inclination is to use EC-pools and failure-domain = OSD.
I was wondering if there is a middle ground - could we define failure-domain = NVMe? I think the map would need to be defined manually in the same way that failure-domain = rack requires information about which nodes are in each rack.
Example: My latest OSD nodes have 8 HDDs and 3 U.2 NVMe. I'd set up the WAL/DB for with HDDs per OSD (wasted space on the 3rd NVMe). Across all my OSD nodes I will have 8 HDDs and either 2 or 3 NVMe devices per node - 15 total NVMe devices. My preferred EC-pool profile is 8+2. It seems that this profile could be safely dispersed across 15 failure domains, resulting in protection against NVMe failure.
Please let me know if this is worth pursuing.
Thanks.
-Dave
-- Dave Hall Binghamton University kdhall@binghamton.edu 607-760-2328 (Cell) 607-777-4641 (Office) _______________________________________________ ceph-users mailing list -- ceph-users@ceph.io To unsubscribe send an email to ceph-users-leave@ceph.io
________________________________ This message is confidential and is for the sole use of the intended recipient(s). It may also be privileged or otherwise protected by copyright or other legal rules. If you have received it by mistake please let us know by reply email and delete it from your system. It is prohibited to copy this message or disclose its content to anyone. Any confidentiality or privilege is not waived or lost by any mistaken delivery or unauthorized disclosure of the message. All messages sent to and from Agoda may be monitored to ensure compliance with company policies, to protect the company's interests and to remove potential malware. Electronic messages may be intercepted, amended, lost or deleted, or contain viruses.
One potential issue is maintenance after a nvme failure. Depending on how the hardware is configured, you will need to bring the whole node down to replace the failed nvme, which could cause PG to become read only if you are close to your min threshold. I think the additional risk is not worth it, but if you move ahead anyway you should also either not use EC, or have a much higher EC ratio, 8-3 or 8-4, or since you have only 48 HDDs, a lower count, 6-3, might be better. On Thu, Mar 11, 2021 at 8:03 AM Dave Hall <kdhall@binghamton.edu> wrote:
Istvan,
I agree that there is always risk with failure-domain < node, especially with EC pools. We are accepting this risk to lower the financial barrier to entry.
In our minds, we have good power protection and new hardware, so the greatest immediate risks for our smaller cluster (approaching 6 OSD nodes and 48 HDDs) are NVMe write exhaustion and HDD failures. Since we have multiple OSDs sharing a single NVMe device it occurs to me that we might want to get Ceph to 'map' against that. In a way, NVMe devices are our 'nodes' at the current size of our cluster.
-Dave
-- Dave Hall Binghamton University
On Wed, Mar 10, 2021 at 10:41 PM Szabo, Istvan (Agoda) < Istvan.Szabo@agoda.com> wrote:
Don't forget if you have server failure you might loose many objects. If the failure domain is osd, it means let's say you have 12 drives in each server, 8+2 EC in an unlucky situation can be located in 1 server also.
Istvan Szabo Senior Infrastructure Engineer --------------------------------------------------- Agoda Services Co., Ltd. e: istvan.szabo@agoda.com ---------------------------------------------------
-----Original Message----- From: Dave Hall <kdhall@binghamton.edu> Sent: Wednesday, March 10, 2021 11:42 PM To: ceph-users <ceph-users@ceph.io> Subject: [ceph-users] Failure Domain = NVMe?
Email received from outside the company. If in doubt don't click links nor open attachments! ________________________________
Hello,
In some documentation I was reading last night about laying out OSDs, it was suggested that if more that one OSD uses the same NVMe drive, the failure-domain should probably be set to node. However, for a small cluster the inclination is to use EC-pools and failure-domain = OSD.
I was wondering if there is a middle ground - could we define failure-domain = NVMe? I think the map would need to be defined manually in the same way that failure-domain = rack requires information about which nodes are in each rack.
Example: My latest OSD nodes have 8 HDDs and 3 U.2 NVMe. I'd set up the WAL/DB for with HDDs per OSD (wasted space on the 3rd NVMe). Across all my OSD nodes I will have 8 HDDs and either 2 or 3 NVMe devices per node - 15 total NVMe devices. My preferred EC-pool profile is 8+2. It seems that this profile could be safely dispersed across 15 failure domains, resulting in protection against NVMe failure.
Please let me know if this is worth pursuing.
Thanks.
-Dave
-- Dave Hall Binghamton University kdhall@binghamton.edu 607-760-2328 (Cell) 607-777-4641 (Office) _______________________________________________ ceph-users mailing list -- ceph-users@ceph.io To unsubscribe send an email to ceph-users-leave@ceph.io
________________________________ This message is confidential and is for the sole use of the intended recipient(s). It may also be privileged or otherwise protected by copyright or other legal rules. If you have received it by mistake please let us know by reply email and delete it from your system. It is prohibited to copy this message or disclose its content to anyone. Any confidentiality or privilege is not waived or lost by any mistaken delivery or unauthorized disclosure of the message. All messages sent to and from Agoda may be monitored to ensure compliance with company policies, to protect the company's interests and to remove potential malware. Electronic messages may be intercepted, amended, lost or deleted, or contain viruses.
_______________________________________________ ceph-users mailing list -- ceph-users@ceph.io To unsubscribe send an email to ceph-users-leave@ceph.io
-- Steven Pine *E * steven.pine@webair.com | *P * 516.938.4100 x *Webair* | 501 Franklin Avenue Suite 200, Garden City NY, 11530 webair.com [image: Facebook icon] <https://www.facebook.com/WebairInc/> [image: Twitter icon] <https://twitter.com/WebairInc> [image: Linkedin icon] <https://www.linkedin.com/company/webair> NOTICE: This electronic mail message and all attachments transmitted with it are intended solely for the use of the addressee and may contain legally privileged proprietary and confidential information. If the reader of this message is not the intended recipient, or if you are an employee or agent responsible for delivering this message to the intended recipient, you are hereby notified that any dissemination, distribution, copying, or other use of this message or its attachments is strictly prohibited. If you have received this message in error, please notify the sender immediately by replying to this message and delete it from your computer.
For EC 8+2 you can get away with 5 hosts by ensuring each host gets 2 shards similar to this: https://ceph.io/planet/erasure-code-on-small-clusters/ If a host dies/goes down you can still recover all data (although at that stage your cluster is no longer available for client io). You shouldn't just consider failure but also maintenance scenarios which will require a node to offline for some time. In particular a ceph upgrades can take some time - especially if something goes wrong. You have no breathing room left at that stage and your cluster will be dead until all nodes are up again On Fri, 12 Mar 2021 at 02:03, Dave Hall <kdhall@binghamton.edu> wrote:
Istvan,
I agree that there is always risk with failure-domain < node, especially with EC pools. We are accepting this risk to lower the financial barrier to entry.
In our minds, we have good power protection and new hardware, so the greatest immediate risks for our smaller cluster (approaching 6 OSD nodes and 48 HDDs) are NVMe write exhaustion and HDD failures. Since we have multiple OSDs sharing a single NVMe device it occurs to me that we might want to get Ceph to 'map' against that. In a way, NVMe devices are our 'nodes' at the current size of our cluster.
-Dave
-- Dave Hall Binghamton University
On Wed, Mar 10, 2021 at 10:41 PM Szabo, Istvan (Agoda) < Istvan.Szabo@agoda.com> wrote:
Don't forget if you have server failure you might loose many objects. If the failure domain is osd, it means let's say you have 12 drives in each server, 8+2 EC in an unlucky situation can be located in 1 server also.
Istvan Szabo Senior Infrastructure Engineer --------------------------------------------------- Agoda Services Co., Ltd. e: istvan.szabo@agoda.com ---------------------------------------------------
-----Original Message----- From: Dave Hall <kdhall@binghamton.edu> Sent: Wednesday, March 10, 2021 11:42 PM To: ceph-users <ceph-users@ceph.io> Subject: [ceph-users] Failure Domain = NVMe?
Email received from outside the company. If in doubt don't click links nor open attachments! ________________________________
Hello,
In some documentation I was reading last night about laying out OSDs, it was suggested that if more that one OSD uses the same NVMe drive, the failure-domain should probably be set to node. However, for a small cluster the inclination is to use EC-pools and failure-domain = OSD.
I was wondering if there is a middle ground - could we define failure-domain = NVMe? I think the map would need to be defined manually in the same way that failure-domain = rack requires information about which nodes are in each rack.
Example: My latest OSD nodes have 8 HDDs and 3 U.2 NVMe. I'd set up the WAL/DB for with HDDs per OSD (wasted space on the 3rd NVMe). Across all my OSD nodes I will have 8 HDDs and either 2 or 3 NVMe devices per node - 15 total NVMe devices. My preferred EC-pool profile is 8+2. It seems that this profile could be safely dispersed across 15 failure domains, resulting in protection against NVMe failure.
Please let me know if this is worth pursuing.
Thanks.
-Dave
-- Dave Hall Binghamton University kdhall@binghamton.edu 607-760-2328 (Cell) 607-777-4641 (Office) _______________________________________________ ceph-users mailing list -- ceph-users@ceph.io To unsubscribe send an email to ceph-users-leave@ceph.io
________________________________ This message is confidential and is for the sole use of the intended recipient(s). It may also be privileged or otherwise protected by copyright or other legal rules. If you have received it by mistake please let us know by reply email and delete it from your system. It is prohibited to copy this message or disclose its content to anyone. Any confidentiality or privilege is not waived or lost by any mistaken delivery or unauthorized disclosure of the message. All messages sent to and from Agoda may be monitored to ensure compliance with company policies, to protect the company's interests and to remove potential malware. Electronic messages may be intercepted, amended, lost or deleted, or contain viruses.
_______________________________________________ ceph-users mailing list -- ceph-users@ceph.io To unsubscribe send an email to ceph-users-leave@ceph.io
Hello, While I appreciate and acknowledge the concerns regarding host failure and maintenance shutdowns, our main concern at this time is data loss. Our use case at this time allows for suspension of client I/0 and/or for full cluster shutdown for maintenance, but loss of data would be catastrophic. It seems that with my current configuration an NVMe failure could cause data loss unless the shards are organized to survive this. So my question is not whether this is prudent, but actually whether this is possible, and if anybody could point to hints on how to implement it. Thanks. -Dave -- Dave Hall Binghamton University kdhall@binghamton.edu 607-760-2328 (Cell) 607-777-4641 (Office) On Thu, Mar 11, 2021 at 1:28 PM Christian Wuerdig < christian.wuerdig@gmail.com> wrote:
For EC 8+2 you can get away with 5 hosts by ensuring each host gets 2 shards similar to this: https://ceph.io/planet/erasure-code-on-small-clusters/ If a host dies/goes down you can still recover all data (although at that stage your cluster is no longer available for client io). You shouldn't just consider failure but also maintenance scenarios which will require a node to offline for some time. In particular a ceph upgrades can take some time - especially if something goes wrong. You have no breathing room left at that stage and your cluster will be dead until all nodes are up again
On Fri, 12 Mar 2021 at 02:03, Dave Hall <kdhall@binghamton.edu> wrote:
Istvan,
I agree that there is always risk with failure-domain < node, especially with EC pools. We are accepting this risk to lower the financial barrier to entry.
In our minds, we have good power protection and new hardware, so the greatest immediate risks for our smaller cluster (approaching 6 OSD nodes and 48 HDDs) are NVMe write exhaustion and HDD failures. Since we have multiple OSDs sharing a single NVMe device it occurs to me that we might want to get Ceph to 'map' against that. In a way, NVMe devices are our 'nodes' at the current size of our cluster.
-Dave
-- Dave Hall Binghamton University
On Wed, Mar 10, 2021 at 10:41 PM Szabo, Istvan (Agoda) < Istvan.Szabo@agoda.com> wrote:
Don't forget if you have server failure you might loose many objects. If the failure domain is osd, it means let's say you have 12 drives in each server, 8+2 EC in an unlucky situation can be located in 1 server also.
Istvan Szabo Senior Infrastructure Engineer --------------------------------------------------- Agoda Services Co., Ltd. e: istvan.szabo@agoda.com ---------------------------------------------------
-----Original Message----- From: Dave Hall <kdhall@binghamton.edu> Sent: Wednesday, March 10, 2021 11:42 PM To: ceph-users <ceph-users@ceph.io> Subject: [ceph-users] Failure Domain = NVMe?
Email received from outside the company. If in doubt don't click links nor open attachments! ________________________________
Hello,
In some documentation I was reading last night about laying out OSDs, it was suggested that if more that one OSD uses the same NVMe drive, the failure-domain should probably be set to node. However, for a small cluster the inclination is to use EC-pools and failure-domain = OSD.
I was wondering if there is a middle ground - could we define failure-domain = NVMe? I think the map would need to be defined manually in the same way that failure-domain = rack requires information about which nodes are in each rack.
Example: My latest OSD nodes have 8 HDDs and 3 U.2 NVMe. I'd set up the WAL/DB for with HDDs per OSD (wasted space on the 3rd NVMe). Across all my OSD nodes I will have 8 HDDs and either 2 or 3 NVMe devices per node - 15 total NVMe devices. My preferred EC-pool profile is 8+2. It seems that this profile could be safely dispersed across 15 failure domains, resulting in protection against NVMe failure.
Please let me know if this is worth pursuing.
Thanks.
-Dave
-- Dave Hall Binghamton University kdhall@binghamton.edu 607-760-2328 (Cell) 607-777-4641 (Office) _______________________________________________ ceph-users mailing list -- ceph-users@ceph.io To unsubscribe send an email to ceph-users-leave@ceph.io
________________________________ This message is confidential and is for the sole use of the intended recipient(s). It may also be privileged or otherwise protected by copyright or other legal rules. If you have received it by mistake please let us know by reply email and delete it from your system. It is prohibited to copy this message or disclose its content to anyone. Any confidentiality or privilege is not waived or lost by any mistaken delivery or unauthorized disclosure of the message. All messages sent to and from Agoda may be monitored to ensure compliance with company policies, to protect the company's interests and to remove potential malware. Electronic messages may be intercepted, amended, lost or deleted, or contain viruses.
_______________________________________________ ceph-users mailing list -- ceph-users@ceph.io To unsubscribe send an email to ceph-users-leave@ceph.io
Setting domain failure on a per node basis will prevent data loss in the case of an nvme failure, you would need multiple nvme failures across different hosts. If data loss is the primary concern then again, you will want a higher EC ratio, 6:3 or 6:4 but with only 6 osds, then 4:2 or even 3:3, or skip EC altogether and use 3x replication, that is likely the safest and best tested use case. You can also take backups of your ceph cluster and send it elsewhere, a tool like backy2 can do this with somewhat minimal setup. but if you have some magical insistence on using the setup you had already determined prior to asking the mailing list then go ahead, and good luck. On Thu, Mar 11, 2021 at 1:56 PM Dave Hall <kdhall@binghamton.edu> wrote:
Hello,
While I appreciate and acknowledge the concerns regarding host failure and maintenance shutdowns, our main concern at this time is data loss. Our use case at this time allows for suspension of client I/0 and/or for full cluster shutdown for maintenance, but loss of data would be catastrophic. It seems that with my current configuration an NVMe failure could cause data loss unless the shards are organized to survive this.
So my question is not whether this is prudent, but actually whether this is possible, and if anybody could point to hints on how to implement it.
Thanks.
-Dave
-- Dave Hall Binghamton University kdhall@binghamton.edu 607-760-2328 (Cell) 607-777-4641 (Office)
On Thu, Mar 11, 2021 at 1:28 PM Christian Wuerdig < christian.wuerdig@gmail.com> wrote:
For EC 8+2 you can get away with 5 hosts by ensuring each host gets 2 shards similar to this: https://ceph.io/planet/erasure-code-on-small-clusters/ If a host dies/goes down you can still recover all data (although at that stage your cluster is no longer available for client io). You shouldn't just consider failure but also maintenance scenarios which will require a node to offline for some time. In particular a ceph upgrades can take some time - especially if something goes wrong. You have no breathing room left at that stage and your cluster will be dead until all nodes are up again
On Fri, 12 Mar 2021 at 02:03, Dave Hall <kdhall@binghamton.edu> wrote:
Istvan,
I agree that there is always risk with failure-domain < node, especially with EC pools. We are accepting this risk to lower the financial barrier to entry.
In our minds, we have good power protection and new hardware, so the greatest immediate risks for our smaller cluster (approaching 6 OSD nodes and 48 HDDs) are NVMe write exhaustion and HDD failures. Since we have multiple OSDs sharing a single NVMe device it occurs to me that we might want to get Ceph to 'map' against that. In a way, NVMe devices are our 'nodes' at the current size of our cluster.
-Dave
-- Dave Hall Binghamton University
On Wed, Mar 10, 2021 at 10:41 PM Szabo, Istvan (Agoda) < Istvan.Szabo@agoda.com> wrote:
Don't forget if you have server failure you might loose many objects. If the failure domain is osd, it means let's say you have 12 drives in each server, 8+2 EC in an unlucky situation can be located in 1 server also.
Istvan Szabo Senior Infrastructure Engineer --------------------------------------------------- Agoda Services Co., Ltd. e: istvan.szabo@agoda.com ---------------------------------------------------
-----Original Message----- From: Dave Hall <kdhall@binghamton.edu> Sent: Wednesday, March 10, 2021 11:42 PM To: ceph-users <ceph-users@ceph.io> Subject: [ceph-users] Failure Domain = NVMe?
Email received from outside the company. If in doubt don't click links nor open attachments! ________________________________
Hello,
In some documentation I was reading last night about laying out OSDs, it was suggested that if more that one OSD uses the same NVMe drive, the failure-domain should probably be set to node. However, for a small cluster the inclination is to use EC-pools and failure-domain = OSD.
I was wondering if there is a middle ground - could we define failure-domain = NVMe? I think the map would need to be defined manually in the same way that failure-domain = rack requires information about which nodes are in each rack.
Example: My latest OSD nodes have 8 HDDs and 3 U.2 NVMe. I'd set up the WAL/DB for with HDDs per OSD (wasted space on the 3rd NVMe). Across all my OSD nodes I will have 8 HDDs and either 2 or 3 NVMe devices per node - 15 total NVMe devices. My preferred EC-pool profile is 8+2. It seems that this profile could be safely dispersed across 15 failure domains, resulting in protection against NVMe failure.
Please let me know if this is worth pursuing.
Thanks.
-Dave
-- Dave Hall Binghamton University kdhall@binghamton.edu 607-760-2328 (Cell) 607-777-4641 (Office) _______________________________________________ ceph-users mailing list -- ceph-users@ceph.io To unsubscribe send an email to ceph-users-leave@ceph.io
________________________________ This message is confidential and is for the sole use of the intended recipient(s). It may also be privileged or otherwise protected by copyright or other legal rules. If you have received it by mistake please let us know by reply email and delete it from your system. It is prohibited to copy this message or disclose its content to anyone. Any confidentiality or privilege is not waived or lost by any mistaken delivery or unauthorized disclosure of the message. All messages sent to and from Agoda may be monitored to ensure compliance with company policies, to protect the company's interests and to remove potential malware. Electronic messages may be intercepted, amended, lost or deleted, or contain viruses.
_______________________________________________ ceph-users mailing list -- ceph-users@ceph.io To unsubscribe send an email to ceph-users-leave@ceph.io
_______________________________________________ ceph-users mailing list -- ceph-users@ceph.io To unsubscribe send an email to ceph-users-leave@ceph.io
-- Steven Pine *E * steven.pine@webair.com | *P * 516.938.4100 x *Webair* | 501 Franklin Avenue Suite 200, Garden City NY, 11530 webair.com [image: Facebook icon] <https://www.facebook.com/WebairInc/> [image: Twitter icon] <https://twitter.com/WebairInc> [image: Linkedin icon] <https://www.linkedin.com/company/webair> NOTICE: This electronic mail message and all attachments transmitted with it are intended solely for the use of the addressee and may contain legally privileged proprietary and confidential information. If the reader of this message is not the intended recipient, or if you are an employee or agent responsible for delivering this message to the intended recipient, you are hereby notified that any dissemination, distribution, copying, or other use of this message or its attachments is strictly prohibited. If you have received this message in error, please notify the sender immediately by replying to this message and delete it from your computer.
Steven, In my current hardware configurations each NVMe supports multiple OSDs. In my earlier nodes it is 8 OSDs sharing one NVMe (which is also too small). In the near term I will add NVMe to those nodes, but I'll still have 5 OSDs some OSDs, and 2 or 3 on all the others. So an NVMe failure will take out at least 2 OSDs. Becasue of this it seems potentially worthwhile to go through the trouble of defining failure domain = nvme to assure maximum resilience. -Dvae -- Dave Hall Binghamton University kdhall@binghamton.edu 607-760-2328 (Cell) 607-777-4641 (Office) On Thu, Mar 11, 2021 at 2:20 PM Steven Pine <steven.pine@webair.com> wrote:
Setting domain failure on a per node basis will prevent data loss in the case of an nvme failure, you would need multiple nvme failures across different hosts. If data loss is the primary concern then again, you will want a higher EC ratio, 6:3 or 6:4 but with only 6 osds, then 4:2 or even 3:3, or skip EC altogether and use 3x replication, that is likely the safest and best tested use case. You can also take backups of your ceph cluster and send it elsewhere, a tool like backy2 can do this with somewhat minimal setup.
but if you have some magical insistence on using the setup you had already determined prior to asking the mailing list then go ahead, and good luck.
On Thu, Mar 11, 2021 at 1:56 PM Dave Hall <kdhall@binghamton.edu> wrote:
Hello,
While I appreciate and acknowledge the concerns regarding host failure and maintenance shutdowns, our main concern at this time is data loss. Our use case at this time allows for suspension of client I/0 and/or for full cluster shutdown for maintenance, but loss of data would be catastrophic. It seems that with my current configuration an NVMe failure could cause data loss unless the shards are organized to survive this.
So my question is not whether this is prudent, but actually whether this is possible, and if anybody could point to hints on how to implement it.
Thanks.
-Dave
-- Dave Hall Binghamton University kdhall@binghamton.edu 607-760-2328 (Cell) 607-777-4641 (Office)
On Thu, Mar 11, 2021 at 1:28 PM Christian Wuerdig < christian.wuerdig@gmail.com> wrote:
For EC 8+2 you can get away with 5 hosts by ensuring each host gets 2 shards similar to this: https://ceph.io/planet/erasure-code-on-small-clusters/ If a host dies/goes down you can still recover all data (although at that stage your cluster is no longer available for client io). You shouldn't just consider failure but also maintenance scenarios which will require a node to offline for some time. In particular a ceph upgrades can take some time - especially if something goes wrong. You have no breathing room left at that stage and your cluster will be dead until all nodes are up again
On Fri, 12 Mar 2021 at 02:03, Dave Hall <kdhall@binghamton.edu> wrote:
Istvan,
I agree that there is always risk with failure-domain < node, especially with EC pools. We are accepting this risk to lower the financial barrier to entry.
In our minds, we have good power protection and new hardware, so the greatest immediate risks for our smaller cluster (approaching 6 OSD nodes and 48 HDDs) are NVMe write exhaustion and HDD failures. Since we have multiple OSDs sharing a single NVMe device it occurs to me that we might want to get Ceph to 'map' against that. In a way, NVMe devices are our 'nodes' at the current size of our cluster.
-Dave
-- Dave Hall Binghamton University
On Wed, Mar 10, 2021 at 10:41 PM Szabo, Istvan (Agoda) < Istvan.Szabo@agoda.com> wrote:
Don't forget if you have server failure you might loose many objects. If the failure domain is osd, it means let's say you have 12 drives in each server, 8+2 EC in an unlucky situation can be located in 1 server also.
Istvan Szabo Senior Infrastructure Engineer --------------------------------------------------- Agoda Services Co., Ltd. e: istvan.szabo@agoda.com ---------------------------------------------------
-----Original Message----- From: Dave Hall <kdhall@binghamton.edu> Sent: Wednesday, March 10, 2021 11:42 PM To: ceph-users <ceph-users@ceph.io> Subject: [ceph-users] Failure Domain = NVMe?
Email received from outside the company. If in doubt don't click links nor open attachments! ________________________________
Hello,
In some documentation I was reading last night about laying out OSDs, it was suggested that if more that one OSD uses the same NVMe drive, the failure-domain should probably be set to node. However, for a small cluster the inclination is to use EC-pools and failure-domain = OSD.
I was wondering if there is a middle ground - could we define failure-domain = NVMe? I think the map would need to be defined manually in the same way that failure-domain = rack requires information about which nodes are in each rack.
Example: My latest OSD nodes have 8 HDDs and 3 U.2 NVMe. I'd set up the WAL/DB for with HDDs per OSD (wasted space on the 3rd NVMe). Across all my OSD nodes I will have 8 HDDs and either 2 or 3 NVMe devices per node - 15 total NVMe devices. My preferred EC-pool profile is 8+2. It seems that this profile could be safely dispersed across 15 failure domains, resulting in protection against NVMe failure.
Please let me know if this is worth pursuing.
Thanks.
-Dave
-- Dave Hall Binghamton University kdhall@binghamton.edu 607-760-2328 (Cell) 607-777-4641 (Office) _______________________________________________ ceph-users mailing list -- ceph-users@ceph.io To unsubscribe send an email to ceph-users-leave@ceph.io
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*E * steven.pine@webair.com | *P * 516.938.4100 x *Webair* | 501 Franklin Avenue Suite 200, Garden City NY, 11530 webair.com [image: Facebook icon] <https://www.facebook.com/WebairInc/> [image: Twitter icon] <https://twitter.com/WebairInc> [image: Linkedin icon] <https://www.linkedin.com/company/webair> NOTICE: This electronic mail message and all attachments transmitted with it are intended solely for the use of the addressee and may contain legally privileged proprietary and confidential information. If the reader of this message is not the intended recipient, or if you are an employee or agent responsible for delivering this message to the intended recipient, you are hereby notified that any dissemination, distribution, copying, or other use of this message or its attachments is strictly prohibited. If you have received this message in error, please notify the sender immediately by replying to this message and delete it from your computer.
In my current hardware configurations each NVMe supports multiple OSDs. In my earlier nodes it is 8 OSDs sharing one NVMe (which is also too small). In the near term I will add NVMe to those nodes, but I'll still have 5 OSDs some OSDs, and 2 or 3 on all the others. So an NVMe failure will take out at least 2 OSDs. Becasue of this it seems potentially worthwhile to go through the trouble of defining failure domain = nvme to assure maximum resilience.
Do you have some test results of the increase of write performance using the osd's with the nvme? Just wondering what can be expected.
Setting the failure domain to host will accomplish nearly the same goal and provide better results during maintenance, host reboots, and of course host failures. But otherwise you can try manually creating crush maps and map a domain failure to nvme and the osds under it, but the additional work and room for error and bugs this can cause is not recommended. On Thu, Mar 11, 2021 at 3:27 PM Dave Hall <kdhall@binghamton.edu> wrote:
Steven,
In my current hardware configurations each NVMe supports multiple OSDs. In my earlier nodes it is 8 OSDs sharing one NVMe (which is also too small). In the near term I will add NVMe to those nodes, but I'll still have 5 OSDs some OSDs, and 2 or 3 on all the others. So an NVMe failure will take out at least 2 OSDs. Becasue of this it seems potentially worthwhile to go through the trouble of defining failure domain = nvme to assure maximum resilience.
-Dvae
-- Dave Hall Binghamton University kdhall@binghamton.edu 607-760-2328 (Cell) 607-777-4641 (Office)
On Thu, Mar 11, 2021 at 2:20 PM Steven Pine <steven.pine@webair.com> wrote:
Setting domain failure on a per node basis will prevent data loss in the case of an nvme failure, you would need multiple nvme failures across different hosts. If data loss is the primary concern then again, you will want a higher EC ratio, 6:3 or 6:4 but with only 6 osds, then 4:2 or even 3:3, or skip EC altogether and use 3x replication, that is likely the safest and best tested use case. You can also take backups of your ceph cluster and send it elsewhere, a tool like backy2 can do this with somewhat minimal setup.
but if you have some magical insistence on using the setup you had already determined prior to asking the mailing list then go ahead, and good luck.
On Thu, Mar 11, 2021 at 1:56 PM Dave Hall <kdhall@binghamton.edu> wrote:
Hello,
While I appreciate and acknowledge the concerns regarding host failure and maintenance shutdowns, our main concern at this time is data loss. Our use case at this time allows for suspension of client I/0 and/or for full cluster shutdown for maintenance, but loss of data would be catastrophic. It seems that with my current configuration an NVMe failure could cause data loss unless the shards are organized to survive this.
So my question is not whether this is prudent, but actually whether this is possible, and if anybody could point to hints on how to implement it.
Thanks.
-Dave
-- Dave Hall Binghamton University kdhall@binghamton.edu 607-760-2328 (Cell) 607-777-4641 (Office)
On Thu, Mar 11, 2021 at 1:28 PM Christian Wuerdig < christian.wuerdig@gmail.com> wrote:
For EC 8+2 you can get away with 5 hosts by ensuring each host gets 2 shards similar to this: https://ceph.io/planet/erasure-code-on-small-clusters/ If a host dies/goes down you can still recover all data (although at that stage your cluster is no longer available for client io). You shouldn't just consider failure but also maintenance scenarios which will require a node to offline for some time. In particular a ceph upgrades can take some time - especially if something goes wrong. You have no breathing room left at that stage and your cluster will be dead until all nodes are up again
On Fri, 12 Mar 2021 at 02:03, Dave Hall <kdhall@binghamton.edu> wrote:
Istvan,
I agree that there is always risk with failure-domain < node, especially with EC pools. We are accepting this risk to lower the financial barrier to entry.
In our minds, we have good power protection and new hardware, so the greatest immediate risks for our smaller cluster (approaching 6 OSD nodes and 48 HDDs) are NVMe write exhaustion and HDD failures. Since we have multiple OSDs sharing a single NVMe device it occurs to me that we might want to get Ceph to 'map' against that. In a way, NVMe devices are our 'nodes' at the current size of our cluster.
-Dave
-- Dave Hall Binghamton University
On Wed, Mar 10, 2021 at 10:41 PM Szabo, Istvan (Agoda) < Istvan.Szabo@agoda.com> wrote:
Don't forget if you have server failure you might loose many objects. If the failure domain is osd, it means let's say you have 12 drives in each server, 8+2 EC in an unlucky situation can be located in 1 server also.
Istvan Szabo Senior Infrastructure Engineer --------------------------------------------------- Agoda Services Co., Ltd. e: istvan.szabo@agoda.com ---------------------------------------------------
-----Original Message----- From: Dave Hall <kdhall@binghamton.edu> Sent: Wednesday, March 10, 2021 11:42 PM To: ceph-users <ceph-users@ceph.io> Subject: [ceph-users] Failure Domain = NVMe?
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Hello,
In some documentation I was reading last night about laying out OSDs, it was suggested that if more that one OSD uses the same NVMe drive, the failure-domain should probably be set to node. However, for a small cluster the inclination is to use EC-pools and failure-domain = OSD.
I was wondering if there is a middle ground - could we define failure-domain = NVMe? I think the map would need to be defined manually in the same way that failure-domain = rack requires information about which nodes are in each rack.
Example: My latest OSD nodes have 8 HDDs and 3 U.2 NVMe. I'd set up the WAL/DB for with HDDs per OSD (wasted space on the 3rd NVMe). Across all my OSD nodes I will have 8 HDDs and either 2 or 3 NVMe devices per node - 15 total NVMe devices. My preferred EC-pool profile is 8+2. It seems that this profile could be safely dispersed across 15 failure domains, resulting in protection against NVMe failure.
Please let me know if this is worth pursuing.
Thanks.
-Dave
-- Dave Hall Binghamton University kdhall@binghamton.edu 607-760-2328 (Cell) 607-777-4641 (Office) _______________________________________________ ceph-users mailing list -- ceph-users@ceph.io To unsubscribe send an email to ceph-users-leave@ceph.io
________________________________ This message is confidential and is for the sole use of the intended recipient(s). It may also be privileged or otherwise protected by copyright or other legal rules. If you have received it by mistake please let us know by reply email and delete it from your system. It is prohibited to copy this message or disclose its content to anyone. Any confidentiality or privilege is not waived or lost by any mistaken delivery or unauthorized disclosure of the message. All messages sent to and from Agoda may be monitored to ensure compliance with company policies, to protect the company's interests and to remove potential malware. Electronic messages may be intercepted, amended, lost or deleted, or contain viruses.
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-- Steven Pine
*E * steven.pine@webair.com | *P * 516.938.4100 x *Webair* | 501 Franklin Avenue Suite 200, Garden City NY, 11530 webair.com [image: Facebook icon] <https://www.facebook.com/WebairInc/> [image: Twitter icon] <https://twitter.com/WebairInc> [image: Linkedin icon] <https://www.linkedin.com/company/webair> NOTICE: This electronic mail message and all attachments transmitted with it are intended solely for the use of the addressee and may contain legally privileged proprietary and confidential information. If the reader of this message is not the intended recipient, or if you are an employee or agent responsible for delivering this message to the intended recipient, you are hereby notified that any dissemination, distribution, copying, or other use of this message or its attachments is strictly prohibited. If you have received this message in error, please notify the sender immediately by replying to this message and delete it from your computer.
-- Steven Pine *E * steven.pine@webair.com | *P * 516.938.4100 x *Webair* | 501 Franklin Avenue Suite 200, Garden City NY, 11530 webair.com [image: Facebook icon] <https://www.facebook.com/WebairInc/> [image: Twitter icon] <https://twitter.com/WebairInc> [image: Linkedin icon] <https://www.linkedin.com/company/webair> NOTICE: This electronic mail message and all attachments transmitted with it are intended solely for the use of the addressee and may contain legally privileged proprietary and confidential information. If the reader of this message is not the intended recipient, or if you are an employee or agent responsible for delivering this message to the intended recipient, you are hereby notified that any dissemination, distribution, copying, or other use of this message or its attachments is strictly prohibited. If you have received this message in error, please notify the sender immediately by replying to this message and delete it from your computer.
participants (5)
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Christian Wuerdig
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Dave Hall
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Marc
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Steven Pine
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Szabo, Istvan (Agoda)