SCSI removable devices problem

SCSI removable devices problem

[Giuliano Pochini]

It seems that 2.6.7 reads the partition table only once: when the scsi unit
is added to the list during boot or when I send the "add-single-device"
command. This is a problem with removable devices because if the drive
hasn't a disk inserted at boot time, attempting to mount a partitioned disk
always results in:

mount: /dev/sdb1 is not a valid block device

Also, bad things may happen (not tested) if a disk was in during boot and I
replace it with another one with a different partitioning.

As a workaround I have to send the "remove-single-device" command after
having unmounted a volume and "add-single-device" after I have inserted a
new one. I don't know when this problem was introduced, sorry.



--
Giuliano.

Re: SCSI removable devices problem

[Randy.Dunlap]

On Sun, 1 Aug 2004 14:19:31 +0200 Giuliano Pochini wrote:

| 
| 
| It seems that 2.6.7 reads the partition table only once: when the scsi unit
| is added to the list during boot or when I send the "add-single-device"
| command. This is a problem with removable devices because if the drive
| hasn't a disk inserted at boot time, attempting to mount a partitioned disk
| always results in:
| 
| mount: /dev/sdb1 is not a valid block device
| 
| Also, bad things may happen (not tested) if a disk was in during boot and I
| replace it with another one with a different partitioning.
| 
| As a workaround I have to send the "remove-single-device" command after
| having unmounted a volume and "add-single-device" after I have inserted a
| new one. I don't know when this problem was introduced, sorry.

I think that it's been this way for some time now...

Does using
	blockdev --rereadpt /dev/sdb1
help?

--
~Randy

Re: SCSI removable devices problem

[Toon van der Pas]

On Sun, Aug 01, 2004 at 09:24:21AM -0700, Randy.Dunlap wrote:
> On Sun, 1 Aug 2004 14:19:31 +0200 Giuliano Pochini wrote:
> 
> > mount: /dev/sdb1 is not a valid block device
> 
> I think that it's been this way for some time now...
> 
> Does using
> 	blockdev --rereadpt /dev/sdb1
> help?

You probably meant to write:
	blockdev --rereadpt /dev/sdb

Regards,
Toon.
-- 
"Debugging is twice as hard as writing the code in the first place.
Therefore, if you write the code as cleverly as possible, you are,
by definition, not smart enough to debug it." - Brian W. Kernighan

Re: SCSI removable devices problem

[Giuliano Pochini]

On Sun, 1 Aug 2004 09:24:21 -0700
"Randy.Dunlap" <rddunlap@osdl.org> wrote:

> On Sun, 1 Aug 2004 14:19:31 +0200 Giuliano Pochini wrote:
> 
> | 
> | 
> | It seems that 2.6.7 reads the partition table only once: when the scsi unit
> | is added to the list during boot or when I send the "add-single-device"
> | command. This is a problem with removable devices because if the drive
> | hasn't a disk inserted at boot time, attempting to mount a partitioned disk
> | always results in:
> | 
> | mount: /dev/sdb1 is not a valid block device
> | 
> | Also, bad things may happen (not tested) if a disk was in during boot and I
> | replace it with another one with a different partitioning.
> | 
> | As a workaround I have to send the "remove-single-device" command after
> | having unmounted a volume and "add-single-device" after I have inserted a
> | new one. I don't know when this problem was introduced, sorry.
> 
> I think that it's been this way for some time now...
> 
> Does using
> 	blockdev --rereadpt /dev/sdb1
> help?

Yes, that works.  But IIRC I didn't need that with linux 2.4. The kernel
should reread the table automatically when it receaves an UNIT_ATTENTION
message from the scsi bus.




--
Giuliano.