Re: Deploying PostgreSQL on CentOS with SSD and Hardware RAID

On 21/05/13 00:16, Merlin Moncure wrote:
> On Sun, May 19, 2013 at 8:07 PM, Toby Corkindale
> <toby.corkindale@strategicdata.com.au> wrote:
>> On 11/05/13 02:25, Merlin Moncure wrote:
>>>
>>> On Fri, May 10, 2013 at 11:11 AM, Evan D. Hoffman
>>> <evandhoffman@gmail.com> wrote:
>>>>
>>>> Not sure of your space requirements, but I'd think a RAID 10 of 8x or
>>>> more
>>>> Samsung 840 Pro 256/512 GB would be the best value.  Using a simple
>>>> mirror
>>>> won't get you the reliability that you want since heavy writing will burn
>>>> the drives out over time, and if you're writing the exact same content to
>>>> both drives, they could likely fail at the same time.  Regardless of the
>>>> underlying hardware you should still follow best practices for
>>>> provisioning
>>>> disks, and raid 10 is the way to go.  I don't know what your budget is
>>>> though.  Anyway, mirrored SSD will probably work fine, but I'd avoid
>>>> using
>>>> just two drives for the reasons above.  I'd suggest at least testing RAID
>>>> 5
>>>> or something else to spread the load around.  Personally, I think the
>>>> ideal
>>>> configuration would be a RAID 10 of at least 8 disks plus 1 hot spare.
>>>> The
>>>> Samsung 840 Pro 256 GB are frequently $200 on sale at Newegg.  YMMV but
>>>> they
>>>> are amazing drives.
>>>
>>>
>>> Samsung 840 has no power loss protection and is therefore useless for
>>> database use IMO unless you don't care about data safety and/or are
>>> implementing redundancy via some other method (say, by synchronous
>>> replication).
>>
>>
>>
>> I believe the original poster was referring to the "840 Pro" model; that
>> model does include a "supercap" for power loss protection.
>
> got a source for that?  I couldn't verify that after some googling.


I'm sorry, I really thought they had made it onto my list of candidates
that included supercaps.. now I'm checking again, I can't find any
evidence to support that claim either. I must have confused them in my
mind with another drive. Sorry about that, and thanks for checking.

-Toby