Re: New server setup - Mailing list pgsql-performance

From Mark Kirkwood
Subject Re: New server setup
Date
Msg-id 51424333.608@catalyst.net.nz
Whole thread Raw
In response to Re: New server setup  (Bruce Momjian <bruce@momjian.us>)
Responses Re: New server setup  (Mark Kirkwood <mark.kirkwood@catalyst.net.nz>)
Re: New server setup  (Bruce Momjian <bruce@momjian.us>)
Re: New server setup  (David Boreham <david_list@boreham.org>)
List pgsql-performance
On 15/03/13 07:54, Bruce Momjian wrote:
> Only use SSDs with a BBU cache, and don't set SSD caches to
> write-through because an SSD needs to cache the write to avoid wearing
> out the chips early, see:
>
>     http://momjian.us/main/blogs/pgblog/2012.html#August_3_2012
>

I not convinced about the need for BBU with SSD - you *can* use them
without one, just need to make sure about suitable longevity and also
the presence of (proven) power off protection (as discussed previously).
It is worth noting that using unproven or SSD known to be lacking power
off protection with a BBU will *not* save you from massive corruption
(or device failure) upon unexpected power loss.

Also, in terms of performance, the faster PCIe SSD do about as well by
themselves as connected to a RAID card with BBU. In fact they will do
better in some cases (the faster SSD can get close to the max IOPS many
RAID cards can handle...so more than a couple of 'em plugged into one
card will be throttled by its limitations).

Cheers

Mark


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