Re: md disks EXTREMELY slow 12.3-STABLE

From: Karl Denninger <karl_at_denninger.net>
Date: Fri, 04 Mar 2022 20:06:03 UTC
On 3/4/2022 14:34, infoomatic wrote:
> On 04.03.22 17:22, Karl Denninger wrote:
>> Load average is 0.3 yet the md0 drive is pinned at 100% busy with just
>> 50 transactions-per-second!
>
> you mean md(4), the memory disk, right? ... just to be sure it is no typo
>
Correct.

I think I've found the issue -- The "-13" build is using a vnode on the 
spinning rust ZFS pool (albeit a fairly high-performance one comprised 
of mirrored vdevs) for backing store.  I'm not sure WHY this winds up 
being so insanely slow, but it does.  I'm going to move it either to 
memory/swap (since I have a bunch) or stick it on the SSD pool since 
creating an md in RAM is, as expected, ridiculously fast.

-- 
Karl Denninger
karl@denninger.net
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