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From: Simon Kirby <sim@hostway.ca>
To: linux-scsi@vger.kernel.org, linux-block@vger.kernel.org
Subject: Unreliable disk detection order in 5.x
Date: Thu, 4 Nov 2021 23:46:23 -0700	[thread overview]
Message-ID: <20211105064623.GD32560@hostway.ca> (raw)

I'm seeing disk detection order changing across reboots on 5.x kernels
(5.4, 5.10, 5.14), but not 4.9, 4.14, 4.19, with megaraid_sas (Dell
PERC_H700). With 13 disks and 5.14.14, the order changes almost always.

I did initially try to bisect this issue, but it seems to become more
rare in earlier kernels, and there are some non-booting problems between
4.x and 5.x.

The most common effect is swapping of sda with sdb, or two neighboring
devices in the list; for example:

# diff -u lsblk-S-5.10.0 lsblk-S-5.10.0-2
--- lsblk-S-5.10.0      2021-11-04 15:23:23.767008360 -0400
+++ lsblk-S-5.10.0-2    2021-11-04 17:34:37.748310196 -0400
@@ -1,6 +1,6 @@
 NAME HCTL       TYPE VENDOR   MODEL      REV TRAN
-sda  0:2:0:0    disk DELL     PERC_H700 2.10
-sdb  0:2:2:0    disk DELL     PERC_H700 2.10
+sda  0:2:2:0    disk DELL     PERC_H700 2.10
+sdb  0:2:0:0    disk DELL     PERC_H700 2.10
 sdc  0:2:3:0    disk DELL     PERC_H700 2.10
 sdd  0:2:4:0    disk DELL     PERC_H700 2.10
 sde  0:2:5:0    disk DELL     PERC_H700 2.10

This is happening on vendor (Debian 5.10.0) and home-built kernels, and
on a variety of hosts. On all kernels, the detection printks come up in
an interesting order, but in older kernels, it always ends up with an
sd-name that is ordered by SCSI ID ascending:

[    2.289776] sd 0:2:0:0: [sda] 999030784 512-byte logical blocks: (512 GB/476 GiB)
[    2.289918] sd 0:2:4:0: [sdd] 11719933952 512-byte logical blocks: (6.00 TB/5.46 TiB)
[    2.289947] sd 0:2:3:0: [sdc] 11719933952 512-byte logical blocks: (6.00 TB/5.46 TiB)
[    2.290032] sd 0:2:6:0: [sdf] 11719933952 512-byte logical blocks: (6.00 TB/5.46 TiB)
[    2.290210] sd 0:2:7:0: [sdg] 11719933952 512-byte logical blocks: (6.00 TB/5.46 TiB)
[    2.290248] sd 0:2:9:0: [sdi] 11719933952 512-byte logical blocks: (6.00 TB/5.46 TiB)
[    2.290323] sd 0:2:2:0: [sdb] 11719933952 512-byte logical blocks: (6.00 TB/5.46 TiB)
[    2.290461] sd 0:2:5:0: [sde] 11719933952 512-byte logical blocks: (6.00 TB/5.46 TiB)
[    2.290476] sd 0:2:8:0: [sdh] 11719933952 512-byte logical blocks: (6.00 TB/5.46 TiB)

Full "dmesg" is saved here: https://0x.ca/sim/ref/5.10.0/dmesg

Any ideas on suggestions on what I could use to track down what changed
here, or ideas on what might have influenced it?

Simon-

             reply	other threads:[~2021-11-05  7:05 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-11-05  6:46 Simon Kirby [this message]
2021-11-05  7:45 ` Unreliable disk detection order in 5.x Damien Le Moal
2021-11-07  2:24   ` Simon Kirby
2021-11-07 19:51     ` Bart Van Assche
2021-11-11  1:01       ` Simon Kirby
2021-11-11  1:16         ` Damien Le Moal
2021-11-11  6:57         ` Hannes Reinecke
2021-11-12  0:11           ` Phillip Susi
2021-11-12  6:38             ` Hannes Reinecke

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