Re: Opinions on SSDs - Mailing list pgsql-admin

On Aug 12, 2013, at 4:15 PM, Lonni J Friedman wrote:

> On Mon, Aug 12, 2013 at 1:05 PM, Bruce Momjian <bruce@momjian.us> wrote:
>> On Mon, Aug 12, 2013 at 08:33:04AM -0700, Joshua D. Drake wrote:
>>>> 1) Has anyone had experience with Intel 520 SSDs?  Are they reliable?
>>>> When they fail, do they fail nicely (ie, failure detected and bad drive
>>>> removed from RAID array) or horribly (data silently corrupted...) ?
>>>
>>> I don't recall if the 520s have powerloss protection but you will
>>> want to check that.
>>
>> I am pretty sure they don't.  The only options are the Intel 320 and
>> 710, I think.  Here is a blog about it:
>>
>>        http://blog.2ndquadrant.com/intel_ssds_lifetime_and_the_32/
>>
>> Look for "Enhanced Power Loss Data Protection".  Intel does not make it
>> easy to find all drive that have it --- you have to look at each spec
>> sheet.
>
> The S3700 series also has power loss data protection:
> http://www.intel.com/content/www/us/en/solid-state-drives/solid-state-drives-dc-s3700-series.html

And the much more affordable S3500 series:

http://www.intel.com/content/www/us/en/solid-state-drives/solid-state-drives-dc-s3500-series.html

The 320 and 710 are still available, but the prices are totally jacked up, which I assume means it's all old stock and
peoplethat need to get exact replacements are the main market at this point. 

We run 4 320s on an SSD-only box and it's been amazing.  We're using ZFS so no hardware RAID, but it does allow us to
pullmembers of each mirrored pair out one by one to take care of both pre-emptive replacement and array growth (started
with160GB drives, on the first refresh moved to 250GB on one pair).  Wear indicator on the replaced drives was at 98%,
sothose got moved to another box for some quick scratch storage.  The next replacement we'll probably cycle the old
SSDsin as ZIL on other (non-db) servers and bring in these new Intel S3500s. 

Another non-traditional and cheap option is to combine some decent spinny drives with SSDs.  The slave to our main
all-SSDbox is a hybrid with 4 10K raptors paired with two small Intel 320s as ZFS ZIL.  The ZIL "absorbs" the sync
writes,so we get ssd-like random write performance but with the data also safe on the traditional spinny drives.
pgbenchon that setup did something like 15K TPS, I've got graphs of that laying around somewhere if anyone's
interested.

The budget hybrid SSD approach is apparently an odd setup, as I've not seen anyone else discuss it. :)

Charles

>
> --
> Sent via pgsql-admin mailing list (pgsql-admin@postgresql.org)
> To make changes to your subscription:
> http://www.postgresql.org/mailpref/pgsql-admin