[dm-devel] SCSI disk IO problem with JBOD/multipath
Mike Snitzer
snitzer at redhat.com
Thu Aug 2 00:51:34 UTC 2012
On Wed, Aug 01 2012 at 7:00pm -0400,
Erich Weiler <weiler at soe.ucsc.edu> wrote:
> So then I had the idea to compile the RDAC multipathing driver and
> create a new initrd that preloads the RDAC driver:
>
> mkinitrd /boot/initrd-$(uname -r)-scsi_dh.img $(uname -r)
> --preload=scsi_dh_rdac
>
> Then I booted with that. It actually did not crash this time, but
> did spew a *ton* of SCSI errors on boot, like these (from dmesg):
snip...
The log you provided does not indicate that the scsi_dh_rdac driver
was actually loaded at boot.
Please add "rdloaddriver=scsi_dh_rdac" to your kernel command line and
see if that helps with all the IO errors you're seeing at boot.
> etc, etc, thousands of times. Just for fun I then tried to tie it
> together with multipathd, using this config:
>
> defaults {
> udev_dir /dev
> polling_interval 5
> path_grouping_policy failover
> getuid_callout "/lib/udev/scsi_id --whitelisted
> --device=/dev/%n"
> path_checker directio
> prio const
> rr_min_io 1000
> rr_weight uniform
> failback manual
> no_path_retry fail
> user_friendly_names yes
> }
>
> blacklist {
> devnode "^(ram|raw|loop|fd|md|dm-|sr|scd|st)[0-9]*"
> devnode "^hd[a-z]
> # Blacklist the root disk (/dev/sda) by wwid - Find the wwid
> via "/lib/udev/scsi_id --page=0x83 --whitelisted --device=/dev/sda"
> wwid "3600508e000000000c3c8e073ff8f3b0c"
> devnode "^dcssblk[0-9]*"
> }
>
> devices {
> device {
> vendor "*"
> product "*"
> getuid_callout "/lib/udev/scsi_id
> --whitelisted --device=/dev/%n"
> path_selector "round-robin 0"
> path_grouping_policy failover
> failback immediate
> rr_weight priorities
> no_path_retry 5
> rr_min_io 1000
> path_checker tur
> prio const
> }
> }
You're not specifying rdac in the multipath conf; therefore multipath
isn't going attach the rdac scsi_dh when each path is activated via
dm-mpath.
> And it *appears* to work:
>
> # multipath -ll
> mpathak (35000c500418ae7db) dm-18 SEAGATE,ST33000651SS
> size=2.7T features='1 queue_if_no_path' hwhandler='0' wp=rw
> |-+- policy='round-robin 0' prio=1 status=active
> | `- 0:0:24:0 sdx 65:112 active ready running
> `-+- policy='round-robin 0' prio=1 status=enabled
> `- 0:0:84:0 sdce 69:32 active ready running
Again, no hwhandler is being specified given: hwhandler='0'
> But I cannot write to the disks, I get I/O errors. When I reboot I
> still get the thousands of SCSI errors on boot from mpt2sas, etc.
> I'm completely stuck. Does anyone have any ideas? Or, is there a
> better place to ask this question?
If you continue to have problems please escalate to Red Hat support and
point them to this mail. They will triage and open a bug accordingly.
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