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Fdisk reports the old size after disk resize

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Operating Systems Linux Red Hat Fdisk reports the old size after disk resize
# 1  
Old 10-03-2013
Fdisk reports the old size after disk resize
Hi,

I'm running a Red Hat Enterprise Linux Server release 5.3 (Tikanga) on VMWare. It is a production system for which I may not get downtime soon. I happened to resize a underlying disk and the changes are not reflecting in the fdisk ouput. Further details are as follows.

The disk which i have extended is /dev/sdv. I have done it as follows

Extended the underlying VMDisk from 38 GB to 50 GB in the Edit windows of the virtual machine


On the OS ( Linux ) I ran the following command for the changes to be picked up

Code:
echo 1 > /sys/class/scsi_disk/1:0:4:0/device/rescan

Following was the output logged in the /var/log/messages

Code:
Oct  3 11:14:08 ########### kernel: SCSI device sdv: 75497472 512-byte hdwr sectors (38655 MB)
Oct  3 11:14:08 ########### kernel: sdv: Write Protect is off
Oct  3 11:14:08 ########### kernel: sdv: cache data unavailable
Oct  3 11:14:08 ########### kernel: sdv: assuming drive cache: write through
Oct  3 11:14:31 ########### kernel: SCSI device sdv: 75497472 512-byte hdwr sectors (38655 MB)
Oct  3 11:14:31 ########### kernel: sdv: Write Protect is off
Oct  3 11:14:31 ########### kernel: sdv: cache data unavailable
Oct  3 11:14:31 ########### kernel: sdv: assuming drive cache: write through
Oct  3 11:44:20 ########### kernel: SCSI device sdv: 104857600 512-byte hdwr sectors (53687 MB)
Oct  3 11:44:20 ########### kernel: sdv: Write Protect is off
Oct  3 11:44:20 ########### kernel: sdv: cache data unavailable
Oct  3 11:44:20 ########### kernel: sdv: assuming drive cache: write through

Now when I did a

Code:
partprobe /dev/sdv

The disk size shown in fdisk did NOT change.


Code:
Disk /dev/sdv: 38.6 GB, 38654705664 bytes
255 heads, 63 sectors/track, 4699 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

   Device Boot      Start         End      Blocks   Id  System
/dev/sdv1               1         872     7004308+  83  Linux
/dev/sdv2             873        4699    30740377+  83  Linux


I have done this in the past without requiring a reboot.Any idea.


Thanks in Advance
# 2  
Old 10-03-2013
rescan won't work if the disk or partitions are open or mounted in any way.
# 3  
Old 10-03-2013
Then what about the log, it shows that the disk was resized.
# 4  
Old 10-03-2013
Altering the partition table is only a matter of writing to the disk, the system won't/can't stop you from doing that if you have the relevant permissions. But Linux won't rescan the MBR of a disk which is in-use in any way.
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