The 512 Gb model is big enough that the SLC cache and performance is
gonna be ok. What would worry me is the lifetime: individual 512 Gb 850
EVOs are rated at 150 Tb over 5 years. Compare that to the Intel S3710 -
400 Gb is rated at 8 Pb over 5 years. These drives are fast enough so
that you *might* write more than 4x 150 = 600 Tb over 5 years...
In addition - Samsung are real cagey about the power loss reliability of
these drives - I suspect that if you do lose power unexpectedly then
data corruption will result (no capacitors to keep RAM cache in sync).
regards
Mark
On 11/04/18 13:39, Matthew Hall wrote:
The most critical bit of advice I've found is setting this preference:
https://amplitude.engineering/how-a-single-postgresql-config-change-improved-slow-query-performance-by-50x-85593b8991b0
I'm using 4 512GB Samsung 850 EVOs in a hardware RAID 10 on a 1U
server with about 144 GB RAM and 8 Xeon cores. I usually burn up CPU
more than I burn up disks or RAM as compared to using magnetic where I
had horrible IO wait percentages, so it seems to be performing quite
well so far.
Matthew Hall
On Apr 9, 2018, at 7:36 PM, Craig James <cjames@xxxxxxxxxxxxxx
<mailto:cjames@xxxxxxxxxxxxxx>> wrote:
One of our four "big iron" (spinning disks) servers went belly up
today. (Thanks, Postgres and pgbackrest! Easy recovery.) We're
planning to move to a cloud service at the end of the year, so bad
timing on this. We didn't want to buy any more hardware, but now it
looks like we have to.
I followed the discussions about SSD drives when they were first
becoming mainstream; at that time, the Intel devices were king. Can
anyone recommend what's a good SSD configuration these days? I don't
think we want to buy a new server with spinning disks.
We're replacing:
8 core (Intel)
48GB memory
12-drive 7200 RPM 500GB
RAID1 (2 disks, OS and WAL log)
RAID10 (8 disks, postgres data dir)
2 spares
Ubuntu 16.04
Postgres 9.6
The current system peaks at about 7000 TPS from pgbench.
Our system is a mix of non-transactional searching (customers) and
transactional data loading (us).
Thanks!
Craig
--
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Craig A. James
Chief Technology Officer
eMolecules, Inc.
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