[dm-devel] sg_persist triggers block kernel event ???

[Christophe Varoqui]

Reproduced on a fairly recent kernel :

cvaroqui at clementine:~$ sudo sg_persist -k /dev/sda
  ATA       SAMSUNG MZMTD512  DXT4
  Peripheral device type: disk
PR in: command not supported

KERNEL[227056.238465] change
/devices/pci0000:00/0000:00:1f.2/ata2/host1/target1:0:0/1:0:0:0/block/sda
(block)
ACTION=change
DEVNAME=/dev/sda
DEVPATH=/devices/pci0000:00/0000:00:1f.2/ata2/host1/target1:0:0/1:0:0:0/block/sda
DEVTYPE=disk
MAJOR=8
MINOR=0
SEQNUM=2603
SUBSYSTEM=block

cvaroqui at clementine:~$ cat /etc/lsb-release
DISTRIB_ID=Ubuntu
DISTRIB_RELEASE=14.04
DISTRIB_CODENAME=trusty
DISTRIB_DESCRIPTION="Ubuntu Trusty Tahr (development branch)"

cvaroqui at clementine:~$ uname -a
Linux clementine 3.13.0-23-generic #45-Ubuntu SMP Fri Apr 4 06:58:38 UTC
2014 x86_64 x86_64 x86_64 GNU/Linux

Regards,
Christophe Varoqui
www.opensvc.com


On Sat, May 3, 2014 at 10:12 PM, Christophe Varoqui <
christophe.varoqui at opensvc.com> wrote:

> Hi list,
>
> I observe this on a debian 7.5 server with a udevadm monitor running in
> the background :
>
> # sg_persist -n -k /dev/sdbh
>   PR generation=0x0, there are NO registered reservation keys
>
> KERNEL[448809.342461] change
> /devices/pci0000:20/0000:20:02.2/0000:24:00.0/host0/rport-0:0-3/target0:0:1/0:0:1:12/block/sdbh
> (block)
> ACTION=change
> DEVNAME=/dev/sdbh
>
> DEVPATH=/devices/pci0000:20/0000:20:02.2/0000:24:00.0/host0/rport-0:0-3/target0:0:1/0:0:1:12/block/sdbh
> DEVTYPE=disk
> MAJOR=67
> MINOR=176
> SEQNUM=261605
> SUBSYSTEM=block
>
> Every sg_persist command, with any options, trigger events.
>
> On this server with more than 200 scsi devices, each receiving one
> read-key and one read-reservation every 10 minutes, this triggers quite a
> eavy load caused by 2 udev triggers :
>
> 1/ multipath -v0 $devpath
> 2/ udisks-lvm-pv-export $pv_uuid
>
>
> Question is, is it normal for a "--in" sg_persist command to trigger a
> change event on the scsi device ? If not, what we can do about it ?
>
> Best regards,
> Christophe Varoqui
> www.opensvc.com
>
>
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