5 Apr
2020
5 Apr
'20
12:21 a.m.
Linuxes don’t require swap at least, maybe BSDs still do but I haven’t run one since the
mid 90s. Back in the day swap had to be at least the size of physmem, but we’re talking
SunOS 4.14 days.
Swap IMHO has been moot for years. It dates to a time when RAM was much more expensive
and capacities less. If you run out of physmem and swap, the real answer is to get more
physmem or bound your processes.
> On Apr 4, 2020, at 5:01 PM, Brent Kennedy <bkennedy(a)cfl.rr.com> wrote:
>
> Forgive me for asking but it seems most OS's require a swap file and when I look
into doing something similar(meaning not having anything), they all say the OS could go
unstable without it. It seems that anyone doing this needs to be 100 certain memory will
not be used at 100% ever or the OS would crash if no swap was there. How are you getting
around this and has it ever been a thing?
>
> Also, for the ceph OSDs, where are you storing the osd and host configurations (
central storage? )?
>
> Regards,
> -Brent
>
> Existing Clusters:
> Test: Nautilus 14.2.2 with 3 osd servers, 1 mon/man, 1 gateway, 2 iscsi gateways (
all virtual on nvme )
> US Production(HDD): Nautilus 14.2.2 with 11 osd servers, 3 mons, 4 gateways, 2 iscsi
gateways
> UK Production(HDD): Nautilus 14.2.2 with 12 osd servers, 3 mons, 4 gateways
> US Production(SSD): Nautilus 14.2.2 with 6 osd servers, 3 mons, 3 gateways, 2 iscsi
gateways
>
>
>
>
> -----Original Message-----
> From: Martin Verges <martin.verges(a)croit.io>
> Sent: Sunday, March 22, 2020 3:50 PM
> To: huxiaoyu(a)horebdata.cn
> Cc: ceph-users <ceph-users(a)ceph.io>
> Subject: [ceph-users] Re: Questions on Ceph cluster without OS disks
>
> Hello Samuel,
>
> we from croit.io don't use NFS to boot up Servers. We copy the OS directly into
the RAM (approximately 0.5-1GB). Think of it like a container, you start it and throw it
away when you no longer need it.
> This way we can save the slots of OS harddisks to add more storage per node and
reduce overall costs as 1GB ram is cheaper then an OS disk and consumes less power.
>
> If our management node is down, nothing will happen to the cluster. No impact, no
downtime. However, you do need the mgmt node to boot up the cluster. So after a very rare
total power outage, your first system would be the mgmt node and then the cluster itself.
But again, if you configure your systems correct, no manual work is required to recover
from that. For everything else, it is possible (but definitely not needed) to deploy our
mgmt node in active/passive HA.
>
> We have multiple hundred installations worldwide in production environments. Our
strong PXE knowledge comes from more than 20 years of datacenter hosting experience and it
never ever failed us in the last >10 years.
>
> The main benefits out of that:
> - Immutable OS freshly booted: Every host has exactly the same version, same library,
kernel, Ceph versions,...
> - OS is heavily tested by us: Every croit deployment has exactly the same image. We
can find errors much faster and hit much fewer errors.
> - Easy Update: Updating OS, Ceph or anything else is just a node reboot.
> No cluster downtime, No service Impact, full automatic handling by our mgmt
Software.
> - No need to install OS: No maintenance costs, no labor required, no other OS
management required.
> - Centralized Logs/Stats: As it is booted in memory, all logs and statistics are
collected on a central place for easy access.
> - Easy to scale: It doesn't matter if you boot 3 oder 300 nodes, all boot the
exact same image in a few seconds.
> .. lots more
>
> Please do not hesitate to contact us directly. We always try to offer an excellent
service and are strongly customer oriented.
>
> --
> Martin Verges
> Managing director
>
> Mobile: +49 174 9335695
> E-Mail: martin.verges(a)croit.io
> Chat: https://t.me/MartinVerges
>
> croit GmbH, Freseniusstr. 31h, 81247 Munich
> CEO: Martin Verges - VAT-ID: DE310638492 Com. register: Amtsgericht Munich HRB
231263
>
> Web: https://croit.io
> YouTube: https://goo.gl/PGE1Bx
>
>
>> Am Sa., 21. März 2020 um 13:53 Uhr schrieb huxiaoyu(a)horebdata.cn <
>> huxiaoyu(a)horebdata.cn>gt;:
>>
>> Hello， Martin，
>>
>> I notice that Croit advocate the use of ceph cluster without OS disks,
>> but with PXE boot.
>>
>> Do you use a NFS server to serve the root file system for each node?
>> such as hosting configuration files, user and password, log files,
>> etc. My question is, will the NFS server be a single point of failure?
>> If the NFS server goes down, the network experience any outage, ceph
>> nodes may not be able to write to the local file systems, possibly leading to
service outage.
>>
>> How do you deal with the above potential issues in production? I am a
>> bit worried...
>>
>> best regards,
>>
>> samuel
>>
>>
>>
>>
>> ------------------------------
>> huxiaoyu(a)horebdata.cn
>>
>>
>>
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