Rereading disk geometry without reboot

Rereading disk geometry without reboot

[Andy]

I am using linux kernel 2.6.9 on a san.  I have file systems on
non-partitioned disks.  I can resize the disk on the SAN, reboot and grow
the XFS file system those disks.  What I would like to avoid rebooting or
even unmounting the filesystem if possible.

Is there any way to get the kernel to re-read the disk geometry and change
the information it holds without rebooting or reloading the module (which is
as bad as a reboot in my case)?

Thanks,

Andy

Re: Rereading disk geometry without reboot

[Jan Engelhardt]

>I am using linux kernel 2.6.9 on a san.  I have file systems on

(What's a SAN?)

>non-partitioned disks.  I can resize the disk on the SAN, reboot and grow
>the XFS file system those disks.  What I would like to avoid rebooting or
>even unmounting the filesystem if possible.
>
>Is there any way to get the kernel to re-read the disk geometry and change
>the information it holds without rebooting or reloading the module (which is
>as bad as a reboot in my case)?

The `fdisk` tool will spit out an ioctl() to make the kernel reread the
partition table (on normal computers, don't know about or what SAN). No need to
reboot there at least.


Jan Engelhardt
-- 
ENOSPC

Re: Rereading disk geometry without reboot

[Randy.Dunlap]

Jan Engelhardt wrote:
>>I am using linux kernel 2.6.9 on a san.  I have file systems on
> 
> 
> (What's a SAN?)
> 
> 
>>non-partitioned disks.  I can resize the disk on the SAN, reboot and grow
>>the XFS file system those disks.  What I would like to avoid rebooting or
>>even unmounting the filesystem if possible.
>>
>>Is there any way to get the kernel to re-read the disk geometry and change
>>the information it holds without rebooting or reloading the module (which is
>>as bad as a reboot in my case)?
> 
> 
> The `fdisk` tool will spit out an ioctl() to make the kernel reread the
> partition table (on normal computers, don't know about or what SAN). No need to
> reboot there at least.

There's 'blockdev --rereadpt' also, but neither of these work
on a mounted filesystem afaik.

-- 
~Randy

Re: Rereading disk geometry without reboot

[Mark Haverkamp]

On Mon, 2004-12-06 at 14:23 -0600, Andy wrote:
> I am using linux kernel 2.6.9 on a san.  I have file systems on
> non-partitioned disks.  I can resize the disk on the SAN, reboot and grow
> the XFS file system those disks.  What I would like to avoid rebooting or
> even unmounting the filesystem if possible.
> 
> Is there any way to get the kernel to re-read the disk geometry and change
> the information it holds without rebooting or reloading the module (which is
> as bad as a reboot in my case)?

You can re-scan a scsi device via sysfs.  You can, for example,

echo 1 > /sys/block/sdc/device/rescan

to rescan that device.

Mark.
 

> 
> Thanks,
> 
> Andy
> -
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-- 
Mark Haverkamp <markh@osdl.org>

Re: Rereading disk geometry without reboot

[Jan Engelhardt]

>There's 'blockdev --rereadpt' also, but neither of these work
>on a mounted filesystem afaik.

Who said editing the ptab of something that's mounted is good?



Jan Engelhardt
-- 
ENOSPC

Re: Rereading disk geometry without reboot

[Robin Holt]

On Mon, Dec 06, 2004 at 02:23:56PM -0600, Andy wrote:
> I am using linux kernel 2.6.9 on a san.  I have file systems on
> non-partitioned disks.  I can resize the disk on the SAN, reboot and grow
> the XFS file system those disks.  What I would like to avoid rebooting or
> even unmounting the filesystem if possible.
> 
> Is there any way to get the kernel to re-read the disk geometry and change
> the information it holds without rebooting or reloading the module (which is
> as bad as a reboot in my case)?

Does anybody know if lvm can do this?

> 
> Thanks,
> 
> Andy
> -
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at  http://www.tux.org/lkml/

Re: Rereading disk geometry without reboot

[Miquel van Smoorenburg]

In article <20041207172812.GD11423@lnx-holt.americas.sgi.com>,
Robin Holt  <holt@sgi.com> wrote:
>On Mon, Dec 06, 2004 at 02:23:56PM -0600, Andy wrote:
>> I am using linux kernel 2.6.9 on a san.  I have file systems on
>> non-partitioned disks.  I can resize the disk on the SAN, reboot and grow
>> the XFS file system those disks.  What I would like to avoid rebooting or
>> even unmounting the filesystem if possible.
>> 
>> Is there any way to get the kernel to re-read the disk geometry and change
>> the information it holds without rebooting or reloading the module (which is
>> as bad as a reboot in my case)?
>
>Does anybody know if lvm can do this?

Yes, with LVM and XFS you can grow a logical volume and resize XFS
to fit without taking the filesytem offline.

Mike.

Re: Rereading disk geometry without reboot

[Andy]

On Tue, Dec 07, 2004 at 08:37:07AM -0800, Mark Haverkamp wrote:
> 
> You can re-scan a scsi device via sysfs.  You can, for example,
> 
> echo 1 > /sys/block/sdc/device/rescan
> 
> to rescan that device.
> 
Yes, and it reports the new size in dmesg, but when I try to grow the xfs
it doesn't grow.  It seems like some part of the kernel is not being told
about the new size of the drive. Any ideas?

Andy