very slow zfs scrub

[Piotr Kucharski]

On Thu, Feb 24, 2011 at 21:00, Adam Vande More <amvandemore at gmail.com> wrote:
>> Wow! What does scrub do that it slows ggate drive almost to halt?
>>
>> What can I do to fix it?
>
> I think network latency is going to have huge impact on performance here.
> Have you tried any ggate or nic tuning?  Would HAST be an option for you?  I
> think it has more performance thought put into it.
>

Well, the network seems rather idle, host and client share the same
1Gb LAN (not sure if the same switch, though) with <0.2ms rtt for 1k
packets in ping. When not scrubbing, sequential reads are
satisfactory. I'm inclined to think some read or write pattern of
scrub that is causing ggate to suck immensely. :/