pvresize after extending RAID array

I have a physical volume consisting of 1 hardware raid array (/dev/sdb).
Now I added some disks to the raid array, extending its size from 4.5
to ~6 TB. The kernel (Linux 2.6.16.51) now correctly reports the new
device size:

# cat /sys/block/sdb/size
12695042048

>From reading the manuals I got the impression, that all that is needed
to be able to use the additional space is "pvresize /dev/sdb".
Unfortunately, it looks like pvresize insists on the old device size:

# pvresize -v -d /dev/sdb
File descriptor 3 left open
Using physical volume(s) on command line
Archiving volume group "raid6_12" metadata (seqno 19).
No change to size of physical volume /dev/sdb.
Resizing volume "/dev/sdb" to 9765416576 sectors.
Updating physical volume "/dev/sdb"
Creating volume group backup "/etc/lvm/backup/raid6_12" (seqno 20).
Physical volume "/dev/sdb" changed
1 physical volume(s) resized / 0 physical volume(s) not resized

Did I miss something? Is there anything to worry about or should I just
go ahead and set the new device size manually:
# pvresize -v -d 6347521024k /dev/sdb
File descriptor 3 left open
Using physical volume(s) on command line
Archiving volume group "raid6_12" metadata (seqno 22).
WARNING: /dev/sdb: real size. You could lose data.
/dev/sdb: Pretending size is 12695042048 not 12695035904 sectors.
No change to size of physical volume /dev/sdb.
Resizing volume "/dev/sdb" to 12695041664 sectors.
Updating physical volume "/dev/sdb"
Creating volume group backup "/etc/lvm/backup/raid6_12" (seqno 23).
Physical volume "/dev/sdb" changed
1 physical volume(s) resized / 0 physical volume(s) not resized

In this case, pvresize comes up with yet another size for the device
(12695035904 sectors) - is this the actual size of the device minus
the space needed for lvm's metadata? Should I manually set to this?

Any comments?

Regards,
Peter Daum


linux-lvm mailing list
linux-lvm (AT) redhat (DOT) com

read the LVM HW-T at http://tldp.org/HWT/LVM-HWT/

Little Addendum:
After a reboot (which of course defeats the purpose a little) lvm
recognizes the new device size:

# pvresize -v -d /dev/sdb
Using physical volume(s) on command line
Archiving volume group "raid6_12" metadata (seqno 30).
Resizing physical volume /dev/sdb from 1192067 to 1549687 extents.
Resizing volume "/dev/sdb" to 12695041664 sectors.
Updating physical volume "/dev/sdb"
Creating volume group backup "/etc/lvm/backup/raid6_12" (seqno 31).
Physical volume "/dev/sdb" changed
1 physical volume(s) resized / 0 physical volume(s) not resized

The figures reported by pvresize are the same as below (except without
warnings this time) so I guess it generally would be o.k in such a case
to just use the kernel's device size and set it manually with
""?


Peter Daum wrote:
I have a physical volume consisting of 1 hardware raid array (/dev/sdb).
Now I added some disks to the raid array, extending its size from 4.5
to ~6 TB. The kernel (Linux 2.6.16.51) now correctly reports the new
device size:

# cat /sys/block/sdb/size
12695042048

>>From reading the manuals I got the impression, that all that is needed
to be able to use the additional space is "pvresize /dev/sdb".
Unfortunately, it looks like pvresize insists on the old device size:

# pvresize -v -d /dev/sdb
File descriptor 3 left open
Using physical volume(s) on command line
Archiving volume group "raid6_12" metadata (seqno 19).
No change to size of physical volume /dev/sdb.
Resizing volume "/dev/sdb" to 9765416576 sectors.
Updating physical volume "/dev/sdb"
Creating volume group backup "/etc/lvm/backup/raid6_12" (seqno 20).
Physical volume "/dev/sdb" changed
1 physical volume(s) resized / 0 physical volume(s) not resized

Did I miss something? Is there anything to worry about or should I just
go ahead and set the new device size manually:
# pvresize -v -d 6347521024k /dev/sdb
File descriptor 3 left open
Using physical volume(s) on command line
Archiving volume group "raid6_12" metadata (seqno 22).
WARNING: /dev/sdb: real size. You could lose data.
/dev/sdb: Pretending size is 12695042048 not 12695035904 sectors.
No change to size of physical volume /dev/sdb.
Resizing volume "/dev/sdb" to 12695041664 sectors.
Updating physical volume "/dev/sdb"
Creating volume group backup "/etc/lvm/backup/raid6_12" (seqno 23).
Physical volume "/dev/sdb" changed
1 physical volume(s) resized / 0 physical volume(s) not resized

In this case, pvresize comes up with yet another size for the device
(12695035904 sectors) - is this the actual size of the device minus
the space needed for lvm's metadata? Should I manually set to this?


linux-lvm mailing list
linux-lvm (AT) redhat (DOT) com

read the LVM HW-T at http://tldp.org/HWT/LVM-HWT/

Exactly which version of LVM2 was this (e.g. output of 'lvm version')?

# cat /sys/block/sdb/size
12695042048

Use the 'blockdev' command - that gets the sizes the same way that lvm2
does.

Alasdair
--
agk (AT) redhat (DOT) com


linux-lvm mailing list
linux-lvm (AT) redhat (DOT) com

read the LVM HW-T at http://tldp.org/HWT/LVM-HWT/

Alasdair G Kergon wrote:
Exactly which version of LVM2 was this (e.g. output of 'lvm version')?
# lvm version
LVM version: 2.02.07 (2006-07-17)
Library version: 1.02.08 (2006-07-17)
Driver version: 4.5.0


># cat /sys/block/sdb/size
>12695042048

Use the 'blockdev' command - that gets the sizes the same way that lvm2
does.

Hopefully not the same way as "blockdev " does it
(which silently fails on that disk; "blockdev /dev/sdb" reports
the correct size in bytes)

Regards,
Peter Daum


linux-lvm mailing list
linux-lvm (AT) redhat (DOT) com

read the LVM HW-T at http://tldp.org/HWT/LVM-HWT/

I too noticed that /sys/block/sdb/size and /proc/partitions reported the size corresponding to the new and correct value after array online expansion. But blockdev didn't and pvresize seems to use the value that blockdev is reporting. I suspected that the block device was locked somehow, so that the update wouldn't happen until the lock was removed. It seems that it's lvm itself that is locking it, because this procedure solved the problem:

pvchange -x n /dev/sdb
pvresize /dev/sdb
pvchange -x y /dev/sdb


[QUOTE=Peter Daum]Alasdair G Kergon wrote:
Exactly which version of LVM2 was this (e.g. output of 'lvm version')?
# lvm version
LVM version: 2.02.07 (2006-07-17)
Library version: 1.02.08 (2006-07-17)
Driver version: 4.5.0


># cat /sys/block/sdb/size
>12695042048

Use the 'blockdev' command - that gets the sizes the same way that lvm2
does.

Hopefully not the same way as "blockdev " does it
(which silently fails on that disk; "blockdev /dev/sdb" reports
the correct size in bytes)

Regards,
Peter Daum