Hi,
don't go there, we tried this with SMR drives, which will slow down to
somewhere around 2-3 IOPS during backfilling/recovery and that renders
the cluster useless for client IO. Things might change in the future,
but for now, I would strongly recommend against SMR.
Go for normal SATA drives with only slightly higher price/capacity ratios.
- mike
On 2/3/17 2:46 PM, Stillwell, Bryan J wrote:
On 2/3/17, 3:23 AM, "ceph-users on behalf of Wido den Hollander"
<ceph-users-boun...@lists.ceph.com on behalf of w...@42on.com> wrote:
Op 3 februari 2017 om 11:03 schreef Maxime Guyot
<maxime.gu...@elits.com>:
Hi,
Interesting feedback!
> In my opinion the SMR can be used exclusively for the RGW.
> Unless it's something like a backup/archive cluster or pool with
little to none concurrent R/W access, you're likely to run out of IOPS
(again) long before filling these monsters up.
That¹s exactly the use case I am considering those archive HDDs for:
something like AWS Glacier, a form of offsite backup probably via
radosgw. The classic Seagate enterprise class HDD provide ³too much²
performance for this use case, I could live with 1Ž4 of the performance
for that price point.
If you go down that route I suggest that you make a mixed cluster for RGW.
A (small) set of OSDs running on top of proper SSDs, eg Samsung SM863 or
PM863 or a Intel DC series.
All pools by default should go to those OSDs.
Only the RGW buckets data pool should go to the big SMR drives. However,
again, expect very, very low performance of those disks.
One of the other concerns you should think about is recovery time when one
of these drives fail. The more OSDs you have, the less this becomes an
issue, but on a small cluster is might take over a day to fully recover
from an OSD failure. Which is a decent amount of time to have degraded
PGs.
Bryan
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