Re: Very slow checkpoints

On Wed, Mar 18, 2015 at 12:58 PM, Steven Jones
<steven(dot)jones1201(at)outlook(dot)com> wrote:
> Yes BBU is on the controller; 1024Mb. It is a HP P410i controller, with write caching turned on the controller; off on disk 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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