[lustre-discuss] ldiskfs patch rejected Rocky 8.6

[Peter Bortas]

Hi Jon,

We have been running ZFS MDSs for 10-ish years, and while I'm sure there is
still some performance to be gained by using ldiskfs due to among other
things the missing support for ZFS ZIL, it's worth it to get rid of the of
the absolute BS mess that ldiskfs is. The big performance hits where before
we all switched away from rotating rust for MDS. Flash storage makes it
pretty manageable.

Without switching to ZFS NSC would frankly not still be using Lustre,
ldiskfs creates too much friction.

Regards,
-- 
Peter Bortas
Swedish National Supercomputer Centre
Linköping University


On Fri, Jul 21, 2023 at 1:34 PM Jon Marshall via lustre-discuss <
lustre-discuss at lists.lustre.org> wrote:

> Hi,
>
> Me again! I now have a successful build of lustre server with ZFS support,
> thanks all for your help with this. I'm now stuck on getting ldiskfs
> support to work - specifically it requires the kernel-debuginfo and
> debugsource packages, which on Rocky 8.6, don't exist for the kernel I'm
> building against (4.18.0-372.9.1.el8.x86_64). I've installed the only ones
> that exist, for kernel 4.18.0-477.15.1.el8_8 and hackily symlinked it to
> the current kernel to get lustre to build against it, which it does, but
> then it fails on applying patches, which I suppose is not surprising. I
> assumed that having the e2fsprogs devel installed would do the trick but
> the build is specific in looking in /usr/src/kernel and
> /usr/src/debug/kernel, neither of which have it.
>
> I'd like ldiskfs support as we currently run this fs on the MDT. However,
> we're only doing that because when we put the filesystem in place (which
> was a while ago) I'd read a fair amount warning against using ZFS on MDT
> due to potential performance issues. I've had a trawl through the mailing
> list and I can't see anyone having issues with newer ZFS versions so I
> guess my question is, is this still a thing? I've been planning to move to
> ZFS at some point anyway and it seems like this would be a good opportunity
> to do so but I thought I'd check and see if anyone had any advice.
>
> Thanks in advance
> Jon
>
> Jon Marshall
>
> High Performance Computing Specialist
>
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