Re: SSD Drives

On Thu, 2014-04-03 at 12:32 -0700, David Rees wrote:
> On Thu, Apr 3, 2014 at 12:13 PM, Merlin Moncure <mmoncure(at)gmail(dot)com> wrote:
> > On Wed, Apr 2, 2014 at 2:37 PM, Bret Stern
> > <bret_stern(at)machinemanagement(dot)com> wrote:
> >> Any opinions/comments on using SSD drives with postgresql?
> >
> > Here's a single S3700 smoking an array of 16 15k drives (poster didn't
> > realize that; was to focused on synthetic numbers):
> > http://dba.stackexchange.com/questions/45224/postgres-write-performance-on-intel-s3700-ssd
>
> I just ran a quick test earlier this week on an old Dell 2970 (2
> Opteron 2387, 16GB RAM) comparing a 6-disk RAID10 with 10k 147GB SAS
> disks to a 2-disk RAID1 with 480GB Intel S3500 SSDs and found the SSDs
> are about 4-6x faster using pgbench and a scaling factor of 1100. Some
> sort of MegaRAID controller according to lspci and has BBU. TPS
> numbers below are approximate.
>
> RAID10 disk array:
> 8 clients: 350 tps
> 16 clients: 530 tps
> 32 clients: 800 tps
>
> RAID1 SSD array:
> 8 clients: 2100 tps
> 16 clients: 2500 tps
> 32 clients: 3100 tps
>
> So yeah, even the slower, cheaper S3500 SSDs are way fast. If your
> write workload isn't too high, the S3500 can work well.

Is a write cycle anywhere on the drive different than a re-write?

Or is a write a write!

They feedback/comments are awesome. I'm shopping..

> We'll see how
> the SMART drive lifetime numbers do once we get into production, but
> right now we estimate they should last at least 5 years and from what
> we've seen it seems that SSDs seem to wear much better than expected.
> If not, we'll pony up and go for the S3700 or perhaps move the xlog
> back on to spinning disks.
>
> -Dave