Reallocating sd device

Reallocating sd device

[Richard Scobie]

Testing a 16 SATA drive (/dev/sd[c-r]1), md RAID, with drives installed
in a hotswap SAS/SATA enclosure.

Failed out /dev/sdd1, ejected the drive from the enclosure, reinserted
it and the system added it back as /dev/sds:

Jun  9 11:24:37 flash2 kernel: mptsas: ioc0: removing sata device,
channel 0, id 30, phy 5
Jun  9 11:24:37 flash2 kernel: sd 4:0:1:0: [sdd] Synchronizing SCSI cache

Jun  9 11:24:37 flash2 kernel: sd 4:0:1:0: [sdd] Result:
hostbyte=DID_NO_CONNECT driverbyte=DRIVER_OK,SUGGEST_OK

Jun  9 11:26:38 flash2 kernel: mptsas: ioc0: attaching sata device,
channel 0, id 30, phy 5

Jun  9 11:26:38 flash2 kernel: scsi 4:0:17:0: Direct-Access     ATA
  WDC WD7500AYYS-0 4G30 PQ: 0 ANSI: 5

Jun  9 11:26:38 flash2 kernel: sd 4:0:17:0: [sds] 1465149168 512-byte
hardware sectors (750156 MB)

Rebooting shows the offline drive back as /dev/sdd.

Is there a safe, (OK to do on a mounted, active array), way of changing
the sds back to sdd, prior to adding it back into the array, without
having to reboot?

Regards,

Richard

Re: Reallocating sd device

[James Bottomley]

On Tue, 2008-06-10 at 07:49 +1200, Richard Scobie wrote:
> Testing a 16 SATA drive (/dev/sd[c-r]1), md RAID, with drives installed
> in a hotswap SAS/SATA enclosure.
> 
> Failed out /dev/sdd1, ejected the drive from the enclosure, reinserted
> it and the system added it back as /dev/sds:
> 
> Jun  9 11:24:37 flash2 kernel: mptsas: ioc0: removing sata device,
> channel 0, id 30, phy 5
> Jun  9 11:24:37 flash2 kernel: sd 4:0:1:0: [sdd] Synchronizing SCSI cache
> 
> Jun  9 11:24:37 flash2 kernel: sd 4:0:1:0: [sdd] Result:
> hostbyte=DID_NO_CONNECT driverbyte=DRIVER_OK,SUGGEST_OK
> 
> Jun  9 11:26:38 flash2 kernel: mptsas: ioc0: attaching sata device,
> channel 0, id 30, phy 5
> 
> Jun  9 11:26:38 flash2 kernel: scsi 4:0:17:0: Direct-Access     ATA
>   WDC WD7500AYYS-0 4G30 PQ: 0 ANSI: 5
> 
> Jun  9 11:26:38 flash2 kernel: sd 4:0:17:0: [sds] 1465149168 512-byte
> hardware sectors (750156 MB)
> 
> Rebooting shows the offline drive back as /dev/sdd.
> 
> Is there a safe, (OK to do on a mounted, active array), way of changing
> the sds back to sdd, prior to adding it back into the array, without
> having to reboot?

Not really ... relying on a specific sdX name has been deprecated for a
while.  To ensure absolute ordering, you should be using the device by
id or by label.

James

Re: Reallocating sd device

[Richard Scobie]

James Bottomley wrote:

> Not really ... relying on a specific sdX name has been deprecated for a
> while.  To ensure absolute ordering, you should be using the device by
> id or by label.
> 
> James

Thanks. I was trying to avoid the extra work of modifying smartd.conf 
files after drives are replaced, which seem to only be able to use 
/dev/sdX, or am I missing something?

Regards,

Richard

Re: Reallocating sd device

[James Bottomley]

On Tue, 2008-06-10 at 08:17 +1200, Richard Scobie wrote:
> James Bottomley wrote:
> 
> > Not really ... relying on a specific sdX name has been deprecated for a
> > while.  To ensure absolute ordering, you should be using the device by
> > id or by label.
> > 
> > James
> 
> Thanks. I was trying to avoid the extra work of modifying smartd.conf 
> files after drives are replaced, which seem to only be able to use 
> /dev/sdX, or am I missing something?

Depends how you're doing it.  I'm pretty sure smartmon is perfectly
capable of using /dev/disk/by-id/X; some of the maintainers are on this
list, so they can comment further.  However, the auto generator for it
(if that's what you're using) always emits /dev/sdX, so I agree you have
a problem with autogenerated files.

James

Re: Reallocating sd device

[Richard Scobie]

James Bottomley wrote:

> Depends how you're doing it.  I'm pretty sure smartmon is perfectly
> capable of using /dev/disk/by-id/X; some of the maintainers are on this
> list, so they can comment further.  However, the auto generator for it
> (if that's what you're using) always emits /dev/sdX, so I agree you have
> a problem with autogenerated files.

Many thanks James, I was unaware of the /dev/disk/by-id/X devices and 
you are correct, smartmontools works fine with these - mdadm also.


Regards,

Richard