[CentOS] Rescan harddisk size without rebooting

Bryan J. Smith thebs413 at earthlink.net
Wed Nov 9 19:44:09 UTC 2005

kadafax <kadafax at gmail.com> wrote:
> Quite there: the new size is reflected...but the disks
> (I've got two virtual disks from the SAN, who are seen like
> scsi disk by the system) are now described as /dev/sdd and
> /dev/sde (initialy /dev/sdb and sdc) 

Aww crap.  Yeah, forgot to mention you might need to release
the previous device assignments.  Kernel 2.6 (CentOS 4) is
better at doing that automagically than kernel 2.4 (CentOS
3).  I assume you're on CentOS 3?

> (below output from a "fdisk -l", the disc which grew is
> initialy sdb). 
> And a "pvdisplay" do not see any new physical extents
> available (perhaps I'm missing something on this, I'm
> totally new from this and way long to be totally cool with
> it)

Part of the problem might be because we probably should have
taken the volume group, and its physical extents, off-line
before doing the previous.  I should have thought this
through more, sorry.  Although it probably won't be of any
issue either.

You could run "vgscan" as see what happens.

> Should I be worried about the "non-valid partition" table
> message? 

Nope.  Next time you boot, it will self-correct.  LVM is
self-contained, so the vgscan handles locating all volumes.

> I can use the LV (mount and work with files), so I don't
> know if it is a problem. Maybe the fact that there is no
> partition table for fdisk is why I can't make it grow?

Hmmm, not sure.  Again, maybe a vgscan would correct things?

> I mean, maybe I should have create first one 
> partition (type LVM), then create a second one with the
> extra size ?
> Here is what I've done to create the logical volume:
> ---
> [root at X ~]# pvcreate /dev/sdb

Well, that won't work because the volumes aren't there on

> [root at X ~]# vgcreate VG-B /dev/sdb
> [root at X ~]# lvcreate -l 166911 VG-B -n LV-B
> // Note: 166911 is the maximum number of physical extents
> available 
> before the grow
> [root at X ~]# mkfs.ext3 /dev/VG-B/LV-B
> ---
> from there I could use the volume.
> ---
> [root at onyx install]# pvdisplay
>   --- Physical volume ---
>   PV Name               /dev/sde
>   VG Name               VG-C
>   PV Size               217.00 GB / not usable 0  
>   Allocatable           yes (but full)
>   PE Size (KByte)       4096
>   Total PE              55551
>   Free PE               0
>   Allocated PE          55551
>   PV UUID              
> w3Q4hA-ALnz-4UuH-fdBB-FGOT-Rn2t-4iG2Vv
>   --- Physical volume ---
>   PV Name               /dev/sdd
>   VG Name               VG-B
>   PV Size               652.00 GB / not usable 0  
>   Allocatable           yes (but full)
>   PE Size (KByte)       4096
>   Total PE              166911
>   Free PE               0
>   Allocated PE          166911
>   PV UUID              
> AFcoa6-6eJl-AAd3-G0Vt-OTXR-niPn-3bTLXu
>   --- Physical volume ---
>   PV Name               /dev/sda2
>   VG Name               VolGroup00
>   PV Size               136.50 GB / not usable 0  
>   Allocatable           yes
>   PE Size (KByte)       32768
>   Total PE              4368
>   Free PE               1
>   Allocated PE          4367
>   PV UUID              
> OjQEXi-u3F8-wCXO-1eZY-W2j0-iZyG-5PwwnB
> ----

Well, you're volumes are clearly showing up on /dev/sdd and
sde.  Those are probably the device(s) you have to target for

Bryan J. Smith                | Sent from Yahoo Mail
mailto:b.j.smith at ieee.org     |  (please excuse any
http://thebs413.blogspot.com/ |   missing headers)

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