Re: Very slow checkpoints - Mailing list pgsql-performance

From Ilya Kosmodemiansky
Subject Re: Very slow checkpoints
Date
Msg-id CAG95seW1=QHDDaO1Juh7g_Zzg_0-ebCZSgzTUdzKBJ05EVWwgg@mail.gmail.com
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In response to Re: Very slow checkpoints  (Steven Jones <steven.jones1201@outlook.com>)
Responses Re: Very slow checkpoints  (Steven Jones <steven.jones1201@outlook.com>)
List pgsql-performance
On Wed, Mar 18, 2015 at 12:58 PM, Steven Jones
<steven.jones1201@outlook.com> wrote:
> Yes BBU is on the controller; 1024Mb. It is a HP P410i controller, with write caching turned on the controller; off
ondisk level. 


vm.dirty_background_bytes=67108864 and vm.dirty_bytes=536870912 looks
resonable for 512MB BBU, you can calculate them for 1024 or
recalculate them for dirty_background_ratio

By the way, which kernel do you use?

> We don't at this stage have any graphs, but we will set it up over the next 24hrs at least.

Do not forget to have iostat statistics on them, at least latency,
%iowait and %util, such parameters are very helpful.

And I am always suspicious about zfs under heavy writes. It is
reliable and quite comfortable in terms of configuration, but for
speed ext4 or xfs with disabled barrier looks more reasonable

>>
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--
Ilya Kosmodemiansky,

PostgreSQL-Consulting.com
tel. +14084142500
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