3 Jun
2021
3 Jun
'21
6:25 p.m.
Hello,
We're planning another batch of OSD nodes for our cluster. Our prior nodes
have been 8 x 12TB SAS drives plus 500GB NVMe per HDD. Due to market
circumstances and the shortage of drives those 12TB SAS drives are in short
supply.
Our integrator has offered an option of 8 x 14TB SATA drives (still
Enterprise). For Ceph, will the switch to SATA carry a performance
difference that I should be concerned about?
Thanks.
-Dave
--
Dave Hall
Binghamton University
kdhall(a)binghamton.edu
3 Jun
3 Jun
6:35 p.m.
I suspect the behavior of the controller and the behavior of the drive
firmware will end up mattering more than SAS vs SATA. As always it's
best if you can test it first before committing to buying a pile of
them. Historically I have seen SATA drives that have performed well as
far as HDDs go though.
Mark
On 6/3/21 4:25 PM, Dave Hall wrote:
Hello,
We're planning another batch of OSD nodes for our cluster. Our prior nodes
have been 8 x 12TB SAS drives plus 500GB NVMe per HDD. Due to market
circumstances and the shortage of drives those 12TB SAS drives are in short
supply.
Our integrator has offered an option of 8 x 14TB SATA drives (still
Enterprise). For Ceph, will the switch to SATA carry a performance
difference that I should be concerned about?
Thanks.
-Dave
--
Dave Hall
Binghamton University
kdhall(a)binghamton.edu
_______________________________________________
ceph-users mailing list -- ceph-users(a)ceph.io
To unsubscribe send an email to ceph-users-leave(a)ceph.io
7:10 p.m.
Agreed. I think oh …. maybe 15-20 years ago there was often a wider difference between
SAS and SATA drives, but with modern queuing etc. my sense is that there is less of an
advantage. Seek and rotational latency I suspect dwarf interface differences wrt
performance. The HBA may be a bigger bottleneck (and way more trouble).
500 GB NVMe seems like a lot per HDD, are you using that as WAL+DB with RGW, or as dmcache
or something?
Depending on your constraints, QLC flash might be more competitive than you think ;)
— aad
I suspect the behavior of the controller and the
behavior of the drive firmware will end up mattering more than SAS vs SATA. As always
it's best if you can test it first before committing to buying a pile of them.
Historically I have seen SATA drives that have performed well as far as HDDs go though.
Mark
On 6/3/21 4:25 PM, Dave Hall wrote:
Hello,
We're planning another batch of OSD nodes for our cluster. Our prior nodes
have been 8 x 12TB SAS drives plus 500GB NVMe per HDD. Due to market
circumstances and the shortage of drives those 12TB SAS drives are in short
supply.
Our integrator has offered an option of 8 x 14TB SATA drives (still
Enterprise). For Ceph, will the switch to SATA carry a performance
difference that I should be concerned about?
Thanks.
-Dave
--
Dave Hall
Binghamton University
kdhall(a)binghamton.edu
_______________________________________________
ceph-users mailing list -- ceph-users(a)ceph.io
To unsubscribe send an email to ceph-users-leave(a)ceph.io
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7:18 p.m.
New subject: SAS vs SATA for OSD - WAL+DB sizing.
Anthony,
I had recently found a reference in the Ceph docs that indicated something
like 40GB per TB for WAL+DB space. For a 12TB HDD that comes out to
480GB. If this is no longer the guideline I'd be glad to save a couple
dollars.
-Dave
--
Dave Hall
Binghamton University
kdhall(a)binghamton.edu
On Thu, Jun 3, 2021 at 6:10 PM Anthony D'Atri <anthony.datri(a)gmail.com>
wrote:
Agreed. I think oh …. maybe 15-20 years ago there was often a wider
difference between SAS and SATA drives, but with modern queuing etc. my
sense is that there is less of an advantage. Seek and rotational latency I
suspect dwarf interface differences wrt performance. The HBA may be a
bigger bottleneck (and way more trouble).
500 GB NVMe seems like a lot per HDD, are you using that as WAL+DB with
RGW, or as dmcache or something?
Depending on your constraints, QLC flash might be more competitive than
you think ;)
— aad
_______________________________________________
ceph-users mailing list -- ceph-users(a)ceph.io
To unsubscribe send an email to ceph-users-leave(a)ceph.io
I suspect the behavior of the controller and the
behavior of the drive
firmware will end up mattering more than SAS vs SATA. As
always it's best
if you can test it first before committing to buying a pile of them.
Historically I have seen SATA drives that have performed well as far as
HDDs go though.
Mark
On 6/3/21 4:25 PM, Dave Hall wrote:
> Hello,
>
> We're planning another batch of OSD nodes for our cluster. Our prior
nodes
> have been 8 x 12TB SAS drives plus 500GB NVMe
per HDD. Due to market
> circumstances and the shortage of drives those 12TB SAS drives are in
short
supply.
Our integrator has offered an option of 8 x 14TB SATA drives (still
Enterprise). For Ceph, will the switch to SATA carry a performance
difference that I should be concerned about?
Thanks.
-Dave
--
Dave Hall
Binghamton University
kdhall(a)binghamton.edu
_______________________________________________
ceph-users mailing list -- ceph-users(a)ceph.io
To unsubscribe send an email to ceph-users-leave(a)ceph.io
_______________________________________________
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To unsubscribe send an email to ceph-users-leave(a)ceph.io
8:38 p.m.
New subject: SAS vs SATA for OSD - WAL+DB sizing.
FWIW, those guidelines try to be sort of a one-size-fits-all
recommendation that may not apply to your situation. Typically RBD has
pretty low metadata overhead so you can get away with smaller DB
partitions. 4% should easily be enough. If you are running heavy RGW
write workloads with small objects, you will almost certainly use more
than 4% for metadata (I've seen worst case up to 50%, but that was
before column family sharding which should help to some extent). Having
said that, bluestore will roll the higher rocksdb levels over to the
slow device and keep the wall, L0, and other lower LSM levels on the
fast device. It's not necessarily the end of the world if you end up
with some of the more rarely used metadata on the HDD but having it on
flash certain is nice.
Mark
On 6/3/21 5:18 PM, Dave Hall wrote:
Anthony,
I had recently found a reference in the Ceph docs that indicated something
like 40GB per TB for WAL+DB space. For a 12TB HDD that comes out to
480GB. If this is no longer the guideline I'd be glad to save a couple
dollars.
-Dave
--
Dave Hall
Binghamton University
kdhall(a)binghamton.edu
On Thu, Jun 3, 2021 at 6:10 PM Anthony D'Atri <anthony.datri(a)gmail.com>
wrote:
Agreed. I think oh …. maybe 15-20 years ago
there was often a wider
difference between SAS and SATA drives, but with modern queuing etc. my
sense is that there is less of an advantage. Seek and rotational latency I
suspect dwarf interface differences wrt performance. The HBA may be a
bigger bottleneck (and way more trouble).
500 GB NVMe seems like a lot per HDD, are you using that as WAL+DB with
RGW, or as dmcache or something?
Depending on your constraints, QLC flash might be more competitive than
you think ;)
— aad
_______________________________________________
ceph-users mailing list -- ceph-users(a)ceph.io
To unsubscribe send an email to ceph-users-leave(a)ceph.io
_______________________________________________
ceph-users mailing list -- ceph-users(a)ceph.io
To unsubscribe send an email to ceph-users-leave(a)ceph.io I suspect the behavior of the controller and the
behavior of the drive
firmware will end up mattering more than SAS vs SATA. As
always it's best
if you can test it first before committing to buying a pile of them.
Historically I have seen SATA drives that have performed well as far as
HDDs go though.
Mark
On 6/3/21 4:25 PM, Dave Hall wrote:
> Hello,
>
> We're planning another batch of OSD nodes for our cluster. Our prior
nodes
> have been 8 x 12TB SAS drives plus 500GB NVMe
per HDD. Due to market
> circumstances and the shortage of drives those 12TB SAS drives are in
short
supply.
Our integrator has offered an option of 8 x 14TB SATA drives (still
Enterprise). For Ceph, will the switch to SATA carry a performance
difference that I should be concerned about?
Thanks.
-Dave
--
Dave Hall
Binghamton University
kdhall(a)binghamton.edu
_______________________________________________
ceph-users mailing list -- ceph-users(a)ceph.io
To unsubscribe send an email to ceph-users-leave(a)ceph.io
_______________________________________________
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To unsubscribe send an email to ceph-users-leave(a)ceph.io
9:29 p.m.
New subject: SAS vs SATA for OSD - WAL+DB sizing.
Mark,
We are running a mix of RGW, RDB, and CephFS. Our CephFS is pretty big,
but we're moving a lot of it to RGW. What prompted me to go looking for a
guideline was a high frequency of Spillover warnings as our cluster filled
up past the 50% mark. That was with 14.2.9, I think. I understand that
some things have changed since, but I think I'd like to have the
flexibility and performance of a generous WAL+DB - the cluster is used to
store research data, and the usage pattern is tending to change as the
research evolves. No telling what our mix will be a year from now.
-Dave
--
Dave Hall
Binghamton University
kdhall(a)binghamton.edu
607-760-2328 (Cell)
607-777-4641 (Office)
On Thu, Jun 3, 2021 at 7:39 PM Mark Nelson <mnelson(a)redhat.com> wrote:
FWIW, those guidelines try to be sort of a
one-size-fits-all
recommendation that may not apply to your situation. Typically RBD has
pretty low metadata overhead so you can get away with smaller DB
partitions. 4% should easily be enough. If you are running heavy RGW
write workloads with small objects, you will almost certainly use more
than 4% for metadata (I've seen worst case up to 50%, but that was
before column family sharding which should help to some extent). Having
said that, bluestore will roll the higher rocksdb levels over to the
slow device and keep the wall, L0, and other lower LSM levels on the
fast device. It's not necessarily the end of the world if you end up
with some of the more rarely used metadata on the HDD but having it on
flash certain is nice.
Mark
On 6/3/21 5:18 PM, Dave Hall wrote:
_______________________________________________
ceph-users mailing list -- ceph-users(a)ceph.io
To unsubscribe send an email to ceph-users-leave(a)ceph.io
Anthony,
I had recently found a reference in the Ceph docs that indicated
something
like 40GB per TB for WAL+DB space. For a 12TB
HDD that comes out to
480GB. If this is no longer the guideline I'd be glad to save a couple
dollars.
-Dave
--
Dave Hall
Binghamton University
kdhall(a)binghamton.edu
On Thu, Jun 3, 2021 at 6:10 PM Anthony D'Atri <anthony.datri(a)gmail.com>
wrote:
> Agreed. I think oh …. maybe 15-20 years ago there was often a wider
> difference between SAS and SATA drives, but with modern queuing etc. my
> sense is that there is less of an advantage. Seek and rotational
latency I
> suspect dwarf interface differences wrt
performance. The HBA may be a
> bigger bottleneck (and way more trouble).
>
> 500 GB NVMe seems like a lot per HDD, are you using that as WAL+DB with
> RGW, or as dmcache or something?
>
> Depending on your constraints, QLC flash might be more competitive than
> you think ;)
>
> — aad
>
>
>> I suspect the behavior of the controller and the behavior of the drive
> firmware will end up mattering more than SAS vs SATA. As always it's
best
if you
can test it first before committing to buying a pile of them.
Historically I have seen SATA drives that have performed well as far as
HDDs go though.
_______________________________________________
ceph-users mailing list -- ceph-users(a)ceph.io
To unsubscribe send an email to ceph-users-leave(a)ceph.io
Mark
On 6/3/21 4:25 PM, Dave Hall wrote:
> Hello,
>
> We're planning another batch of OSD nodes for our cluster. Our prior
nodes
> have been 8 x 12TB SAS drives plus 500GB NVMe
per HDD. Due to market
> circumstances and the shortage of drives those 12TB SAS drives are in
short
> supply.
>
> Our integrator has offered an option of 8 x 14TB SATA drives (still
> Enterprise). For Ceph, will the switch to SATA carry a performance
> difference that I should be concerned about?
>
> Thanks.
>
> -Dave
>
> --
> Dave Hall
> Binghamton University
> kdhall(a)binghamton.edu
> _______________________________________________
> ceph-users mailing list -- ceph-users(a)ceph.io
> To unsubscribe send an email to ceph-users-leave(a)ceph.io
>
_______________________________________________
ceph-users mailing list -- ceph-users(a)ceph.io
To unsubscribe send an email to ceph-users-leave(a)ceph.io
_______________________________________________
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9:43 p.m.
New subject: SAS vs SATA for OSD - WAL+DB sizing.
In releases before … Pacific I think, there are certain discrete capacities that DB will
actually utilize: the sum of RocksDB levels. Lots of discussion in the archives. AIUI in
those releases, with a 500 GB BlueStore WAL+DB device, you’ll with default settings only
actually use ~~300 GB most of the time, though the extra might accelerate compaction.
With Pacific I believe code was merged that shards OSD RocksDB to make better use of
arbitrary partition / devices sizes.
With older releases one can (or so I’ve read) game this a bit by carefully adjusting
rocksdb.max-bytes-for-level-base; ISTR that Karan did that for his impressive 10 Billion
Object exercise.
I’ve seen threads on the list over the past couple of years that seemed to show spillover
despite the DB device not being fully utilized; I hope that’s since been addressed.
My understanding is that with column sharding, compaction only takes place on a fraction
of the DB at any one time, so the transient space used for it (and thus prone to
spillover) should be lessened.
I may of course be out of my Vulcan mind, but HTH.
— aad
On Jun 3, 2021, at 5:29 PM, Dave Hall
<kdhall(a)binghamton.edu> wrote:
Mark,
We are running a mix of RGW, RDB, and CephFS. Our CephFS is pretty big,
but we're moving a lot of it to RGW. What prompted me to go looking for a
guideline was a high frequency of Spillover warnings as our cluster filled
up past the 50% mark. That was with 14.2.9, I think. I understand that
some things have changed since, but I think I'd like to have the
flexibility and performance of a generous WAL+DB - the cluster is used to
store research data, and the usage pattern is tending to change as the
research evolves. No telling what our mix will be a year from now.
-Dave
--
Dave Hall
Binghamton University
kdhall(a)binghamton.edu
607-760-2328 (Cell)
607-777-4641 (Office)
On Thu, Jun 3, 2021 at 7:39 PM Mark Nelson <mnelson(a)redhat.com> wrote:
FWIW, those guidelines try to be sort of a
one-size-fits-all
recommendation that may not apply to your situation. Typically RBD has
pretty low metadata overhead so you can get away with smaller DB
partitions. 4% should easily be enough. If you are running heavy RGW
write workloads with small objects, you will almost certainly use more
than 4% for metadata (I've seen worst case up to 50%, but that was
before column family sharding which should help to some extent). Having
said that, bluestore will roll the higher rocksdb levels over to the
slow device and keep the wall, L0, and other lower LSM levels on the
fast device. It's not necessarily the end of the world if you end up
with some of the more rarely used metadata on the HDD but having it on
flash certain is nice.
Mark
On 6/3/21 5:18 PM, Dave Hall wrote:
_______________________________________________
ceph-users mailing list -- ceph-users(a)ceph.io
To unsubscribe send an email to ceph-users-leave(a)ceph.io
_______________________________________________
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To unsubscribe send an email to ceph-users-leave(a)ceph.io Anthony,
I had recently found a reference in the Ceph docs that indicated
something
like 40GB per TB for WAL+DB space. For a 12TB
HDD that comes out to
480GB. If this is no longer the guideline I'd be glad to save a couple
dollars.
-Dave
--
Dave Hall
Binghamton University
kdhall(a)binghamton.edu
On Thu, Jun 3, 2021 at 6:10 PM Anthony D'Atri <anthony.datri(a)gmail.com>
wrote:
> Agreed. I think oh …. maybe 15-20 years ago there was often a wider
> difference between SAS and SATA drives, but with modern queuing etc. my
> sense is that there is less of an advantage. Seek and rotational
latency I
> suspect dwarf interface differences wrt
performance. The HBA may be a
> bigger bottleneck (and way more trouble).
>
> 500 GB NVMe seems like a lot per HDD, are you using that as WAL+DB with
> RGW, or as dmcache or something?
>
> Depending on your constraints, QLC flash might be more competitive than
> you think ;)
>
> — aad
>
>
>> I suspect the behavior of the controller and the behavior of the drive
> firmware will end up mattering more than SAS vs SATA. As always it's
best
if you
can test it first before committing to buying a pile of them.
Historically I have seen SATA drives that have performed well as far as
HDDs go though.
>
> Mark
>
> On 6/3/21 4:25 PM, Dave Hall wrote:
>> Hello,
>>
>> We're planning another batch of OSD nodes for our cluster. Our prior
nodes
>> have been 8 x 12TB SAS drives plus 500GB NVMe per HDD. Due to market
>> circumstances and the shortage of drives those 12TB SAS drives are in
short
>> supply.
>>
>> Our integrator has offered an option of 8 x 14TB SATA drives (still
>> Enterprise). For Ceph, will the switch to SATA carry a performance
>> difference that I should be concerned about?
>>
>> Thanks.
>>
>> -Dave
>>
>> --
>> Dave Hall
>> Binghamton University
>> kdhall(a)binghamton.edu
>> _______________________________________________
>> ceph-users mailing list -- ceph-users(a)ceph.io
>> To unsubscribe send an email to ceph-users-leave(a)ceph.io
>>
> _______________________________________________
> ceph-users mailing list -- ceph-users(a)ceph.io
> To unsubscribe send an email to ceph-users-leave(a)ceph.io
_______________________________________________
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6:43 p.m.
Dave-
These are just general observations of how SATA drives operate in storage
clusters.
It has been a while since I have run a storage cluster with SATA drives,
but in the past I did notice that SATA drives would drop off the
controllers pretty frequently. Depending on many factors, it may just be a
brief outage where the drive wasn't available but recoverable, sometimes it
meant going into the controller and rescanning for drives before they could
be added back to the system, the worst was one chassis that would mark the
drives as failed after the drive dropped off a certain number of times and
the vendor could not correct the issue with a firmware update and had to
replace the storage chassis.
Regards,
-Jamie
On Thu, Jun 3, 2021 at 5:26 PM Dave Hall <kdhall(a)binghamton.edu> wrote:
Hello,
We're planning another batch of OSD nodes for our cluster. Our prior nodes
have been 8 x 12TB SAS drives plus 500GB NVMe per HDD. Due to market
circumstances and the shortage of drives those 12TB SAS drives are in short
supply.
Our integrator has offered an option of 8 x 14TB SATA drives (still
Enterprise). For Ceph, will the switch to SATA carry a performance
difference that I should be concerned about?
Thanks.
-Dave
--
Dave Hall
Binghamton University
kdhall(a)binghamton.edu
_______________________________________________
ceph-users mailing list -- ceph-users(a)ceph.io
To unsubscribe send an email to ceph-users-leave(a)ceph.io
--
Jamie Fargen
Senior Consultant
jfargen(a)redhat.com
813-817-4430
1063
days inactive
1064
days old
7 comments
4 participants
participants (4)
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Mark Nelson