Re: git: 730ea72c706e - main - cam(4): Limit search for disks in SES enclosure by single bus

On Tue, Oct 5, 2021 at 1:41 PM Alexander Motin <mav@freebsd.org> wrote:
>
> On 05.10.2021 15:14, Alan Somers wrote:
> > On Tue, Oct 5, 2021 at 1:04 PM Alexander Motin <mav@freebsd.org> wrote:
> >>
> >> The branch main has been updated by mav:
> >>
> >> URL: https://cgit.FreeBSD.org/src/commit/?id=730ea72c706ef8e025616772cfd86fd89ed3d42e
> >>
> >> commit 730ea72c706ef8e025616772cfd86fd89ed3d42e
> >> Author:     Alexander Motin <mav@FreeBSD.org>
> >> AuthorDate: 2021-10-05 19:01:16 +0000
> >> Commit:     Alexander Motin <mav@FreeBSD.org>
> >> CommitDate: 2021-10-05 19:01:16 +0000
> >>
> >>     cam(4): Limit search for disks in SES enclosure by single bus
> >>
> >>     At least for SAS that we only support now disks are typically
> >>     connected to the same bus as the enclosure.  Limiting the search
> >>     scope makes it much faster on systems with multiple buses and
> >>     thousands of disks.
> >>
> >>     Reviewed by:    imp
> >>     MFC after:      2 weeks
> >>     Sponsored by:   iXsystems, Inc.
> >>     Differential Revision:  https://reviews.freebsd.org/D32305
> >> ---
> >>  sys/cam/scsi/scsi_enc_ses.c | 8 ++++++++
> >>  1 file changed, 8 insertions(+)
> >>
> >> diff --git a/sys/cam/scsi/scsi_enc_ses.c b/sys/cam/scsi/scsi_enc_ses.c
> >
> >
> > Sounds juicy.  Do you have any benchmarks?
>
> I don't think we've benchmarked that system with payload yet, if that is
> what you mean, polishing usability.  But I don't think there can be too
> much interesting, since big speeds don't require so many HDDs these
> days, but much smaller number of SSDs instead.  This particular system
> is about capacity -- ~20PiB raw on 1248 disks in one ZFS pool. :)
>
> --
> Alexander Motin

1248 disks?  That's huge.  But I'm not asking about throughput.  Your
commit message said "much faster".  What operation is "much faster"?
Enumerating disks at startup?  That would be useful.
-Alan