Adam,
What David said before about SSD drives is very important. I will tell
you another way: use enterprise grade SSD drives, not consumer grade.
Also, pay attention to endurance.
The only suitable drive for Ceph I see in your tests is SSDSC2BB150G7,
and probably it isn't even the most suitable SATA SSD disk from Intel;
better use S3610 o S3710 series.
Cheers
Eneko
El 25/04/17 a las 21:02, Adam Carheden escribió:
On 04/25/2017 11:57 AM, David wrote:
On 19 Apr 2017 18:01, "Adam Carheden" <carheden@xxxxxxxx
<mailto:carheden@xxxxxxxx>> wrote:
Does anyone know if XFS uses a single thread to write to it's journal?
You probably know this but just to avoid any confusion, the journal in
this context isn't the metadata journaling in XFS, it's a separate
journal written to by the OSD daemons
Ha! I didn't know that.
I think the number of threads per OSD is controlled by the 'osd op
threads' setting which defaults to 2
So the ideal (for performance) CEPH cluster would be one SSD per HDD
with 'osd op threads' set to whatever value fio shows as the optimal
number of threads for that drive then?
I would avoid the SanDisk and Hynix. The s3500 isn't too bad. Perhaps
consider going up to a 37xx and putting more OSDs on it. Of course with
the caveat that you'll lose more OSDs if it goes down.
Why would you avoid the SanDisk and Hynix? Reliability (I think those
two are both TLC)? Brand trust? If it's my benchmarks in my previous
email, why not the Hynix? It's slower than the Intel, but sort of
decent, at lease compared to the SanDisk.
My final numbers are below, including an older Samsung Evo (MCL I think)
which did horribly, though not as bad as the SanDisk. The Seagate is a
10kRPM SAS "spinny" drive I tested as a control/SSD-to-HDD comparison.
SanDisk SDSSDA240G, fio 1 jobs: 7.0 MB/s (5 trials)
SanDisk SDSSDA240G, fio 2 jobs: 7.6 MB/s (5 trials)
SanDisk SDSSDA240G, fio 4 jobs: 7.5 MB/s (5 trials)
SanDisk SDSSDA240G, fio 8 jobs: 7.6 MB/s (5 trials)
SanDisk SDSSDA240G, fio 16 jobs: 7.6 MB/s (5 trials)
SanDisk SDSSDA240G, fio 32 jobs: 7.6 MB/s (5 trials)
SanDisk SDSSDA240G, fio 64 jobs: 7.6 MB/s (5 trials)
HFS250G32TND-N1A2A 30000P10, fio 1 jobs: 4.2 MB/s (5 trials)
HFS250G32TND-N1A2A 30000P10, fio 2 jobs: 0.6 MB/s (5 trials)
HFS250G32TND-N1A2A 30000P10, fio 4 jobs: 7.5 MB/s (5 trials)
HFS250G32TND-N1A2A 30000P10, fio 8 jobs: 17.6 MB/s (5 trials)
HFS250G32TND-N1A2A 30000P10, fio 16 jobs: 32.4 MB/s (5 trials)
HFS250G32TND-N1A2A 30000P10, fio 32 jobs: 64.4 MB/s (5 trials)
HFS250G32TND-N1A2A 30000P10, fio 64 jobs: 71.6 MB/s (5 trials)
SAMSUNG SSD, fio 1 jobs: 2.2 MB/s (5 trials)
SAMSUNG SSD, fio 2 jobs: 3.9 MB/s (5 trials)
SAMSUNG SSD, fio 4 jobs: 7.1 MB/s (5 trials)
SAMSUNG SSD, fio 8 jobs: 12.0 MB/s (5 trials)
SAMSUNG SSD, fio 16 jobs: 18.3 MB/s (5 trials)
SAMSUNG SSD, fio 32 jobs: 25.4 MB/s (5 trials)
SAMSUNG SSD, fio 64 jobs: 26.5 MB/s (5 trials)
INTEL SSDSC2BB150G7, fio 1 jobs: 91.2 MB/s (5 trials)
INTEL SSDSC2BB150G7, fio 2 jobs: 132.4 MB/s (5 trials)
INTEL SSDSC2BB150G7, fio 4 jobs: 138.2 MB/s (5 trials)
INTEL SSDSC2BB150G7, fio 8 jobs: 116.9 MB/s (5 trials)
INTEL SSDSC2BB150G7, fio 16 jobs: 61.8 MB/s (5 trials)
INTEL SSDSC2BB150G7, fio 32 jobs: 22.7 MB/s (5 trials)
INTEL SSDSC2BB150G7, fio 64 jobs: 16.9 MB/s (5 trials)
SEAGATE ST9300603SS, fio 1 jobs: 0.7 MB/s (5 trials)
SEAGATE ST9300603SS, fio 2 jobs: 0.9 MB/s (5 trials)
SEAGATE ST9300603SS, fio 4 jobs: 1.6 MB/s (5 trials)
SEAGATE ST9300603SS, fio 8 jobs: 2.0 MB/s (5 trials)
SEAGATE ST9300603SS, fio 16 jobs: 4.6 MB/s (5 trials)
SEAGATE ST9300603SS, fio 32 jobs: 6.9 MB/s (5 trials)
SEAGATE ST9300603SS, fio 64 jobs: 0.6 MB/s (5 trials)
For those who come across this and are looking for drives for purposes
other than CEPH, those are all sequential write numbers with caching
disabled, a very CEPH-journal-specific test. The SanDisk held it's own
against the Intel using some benchmarks on Windows that didn't disable
caching. It may very well be a perfectly good drive for other purposes.
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