[CentOS] Rescan harddisk size without rebooting

kadafax kadafax at gmail.com
Wed Nov 9 17:44:00 UTC 2005

Thanks for reply Bryan,
in fact since the mounted FS is for backup purpose only, it's not a big 
deal to un-mount it (far better than disabling the ldap service with a 
reboot). I've checked google and the result it gives seems to be too 
heavy for this production server (new scsi driver etc.). So if you have 
a solution who is working on un-mounted volume, I'm very interrested.

PS: The SAN is an AX100sc from EMC. The host adapter is a QLA200 from 
QLogic. OS: CentOS 4.2

Bryan J. Smith wrote:

>On Wed, 2005-11-09 at 11:52 +0100, kadafax wrote:
>>Hi list,
>>I have a SAN attached to a CentOS 4.2 server. I have expanded the size 
>>of the virtual disk within the SAN (by adding a new HD to the disk pool) 
>>and need CentOS to see the new size (CentOS see it as /dev/sdb). I'm 
>>using LVM. Do you  know a method for the Volume Group to see that one of 
>>its harddisk is now bigger, without rebooting (it's not a problem with a 
>>reboot but since the LDAP directory is on this server, it is problematic).
>Anytime you expand what Linux sees as a "physical device" -- even though
>it's a volume over a FC HBA -- that is not always easy to address.  You
>typically have to rescan the SCSI bus (which is what the FC HBA presents
>the storage as).  Unfortunately, if you have filesystems mounted on that
>device, they may not update -- even if you're using LVM atop.
>Last time I checked, there was no single command to rescan the SCSI bus
>in RHEL.  Ironically enough, I typically just do a Google search for
>"Linux SCSI bus scan" and run the few commands listed whenever I need to
>do so.  But I don't know what that might do to your running storage --
>it could kill your mounts.

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