* [linux-lvm] [Q] LVM snapshot volume extendable?
@ 2003-01-12 6:11 Sean Oh
2003-01-12 7:09 ` Alasdair G Kergon
2003-01-12 7:09 ` jon+lvm
0 siblings, 2 replies; 6+ messages in thread
From: Sean Oh @ 2003-01-12 6:11 UTC (permalink / raw)
To: linux-lvm
Hi
I am using LVM 1.0.6, kernel 2.4.20 and XFS (from linux-2.4-xfs CVS).
My question is that is the snapshot volume extendable?
My environment is as follows:
/dev/vg01/lv01 ---> XFS, 2G
/dev/vg01/lv01_snap --> 256M, snapshot for /dev/vg01/lv01, mounted under
/snap with ro,nouuid,usrquota,grpquota,noatime
Now I have wrote a small shell scripts that if lv01_snap is more than 50%
full, automatically increase the lv01_snap. But it seems to me that it does
not work well..
What I did in the shell scripts are 'lvextend -L+256M /dev/vg01/lv01_snap'
with/without 'xfs_growfs /snap'.
After umounting the /snap and trying to remount /snap, it complaints as
below
XFS: recovery required required on read-only device
XFS: write access unavailabe, cannot proceed
XFS: log mount/recovery failed
XFS: log mount failed
mount: wrong fs type, bad option, bad superblock on /dev/vg01/lv01,
or too many mounted file systems
(aren't you trying to mount an extended partition,
instead of some logical partition inside?)
BTW, extending the original lv01 works fine with lvextend and xfs_growfs.
Could someone please help?
Thanks in advance
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [linux-lvm] [Q] LVM snapshot volume extendable? 2003-01-12 6:11 [linux-lvm] [Q] LVM snapshot volume extendable? Sean Oh @ 2003-01-12 7:09 ` Alasdair G Kergon 2003-01-12 7:09 ` jon+lvm 1 sibling, 0 replies; 6+ messages in thread From: Alasdair G Kergon @ 2003-01-12 7:09 UTC (permalink / raw) To: linux-lvm On Sun, Jan 12, 2003 at 09:12:07PM +0900, Sean Oh wrote: > What I did in the shell scripts are 'lvextend -L+256M /dev/vg01/lv01_snap' > with/without 'xfs_growfs /snap'. The snapshot volume does not hold a filesystem - it is just a storage area for deltas that enable the system to reconstruct a filesystem. So you don't need to run xfs utilities on it to make more space. [But of course some people might want to run them on writeable snapshots (needs kernel patch) for testing the effect of utilities.] Alasdair -- agk@uk.sistina.com ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [linux-lvm] [Q] LVM snapshot volume extendable? 2003-01-12 6:11 [linux-lvm] [Q] LVM snapshot volume extendable? Sean Oh 2003-01-12 7:09 ` Alasdair G Kergon @ 2003-01-12 7:09 ` jon+lvm 2003-01-12 7:29 ` Sean Oh 1 sibling, 1 reply; 6+ messages in thread From: jon+lvm @ 2003-01-12 7:09 UTC (permalink / raw) To: linux-lvm On Sun, Jan 12, 2003 at 09:12:07PM +0900, Sean Oh wrote: > Hi > > I am using LVM 1.0.6, kernel 2.4.20 and XFS (from linux-2.4-xfs CVS). > > My question is that is the snapshot volume extendable? yes, just use lvextend. > My environment is as follows: > > /dev/vg01/lv01 ---> XFS, 2G > /dev/vg01/lv01_snap --> 256M, snapshot for /dev/vg01/lv01, mounted under > /snap with ro,nouuid,usrquota,grpquota,noatime > > Now I have wrote a small shell scripts that if lv01_snap is more than 50% > full, automatically increase the lv01_snap. But it seems to me that it does > not work well.. I wrote one too, but rather than 50% used, i used XX MB free space. > What I did in the shell scripts are 'lvextend -L+256M /dev/vg01/lv01_snap' > with/without 'xfs_growfs /snap'. you dont need to grow the filesystem on the snapshot. > After umounting the /snap and trying to remount /snap, it complaints as > below you dont need to unmount it A LVM snapshot works by allocating a new "PE table". This means. (# is allocated, - is not, and | is the end) LV: |-#################--##---#####-| snapshot: |---| so, you change something in the LV LV: |-#############+###--##---#####-| snapshot: |#--| Only the block that is actualy changed is moved to the snapshot. If you need alot of changes your snapshot should be big, if you dont change alot, you can use a much smaller snapshot. JonB ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [linux-lvm] [Q] LVM snapshot volume extendable? 2003-01-12 7:09 ` jon+lvm @ 2003-01-12 7:29 ` Sean Oh 2003-01-12 11:16 ` jon+lvm 0 siblings, 1 reply; 6+ messages in thread From: Sean Oh @ 2003-01-12 7:29 UTC (permalink / raw) To: linux-lvm Thanks for the replay. Well, just doing 'lvextend' does not work for me here. Is there any other thing that I need to look for? This is what I do for testing the extending the snapshot volume ------------------ [root@storageone root]# df -k Filesystem 1K-blocks Used Available Use% Mounted on /dev/sda1 5903668 1476712 4426956 26% / /dev/vg01/lv01 567079312 2200 567077112 1% /vg01/lv01 /dev/vg01/lv01_snap0112_2159 567079312 2200 567077112 1% /snap/lv01_snap0112_2159 [root@storageone root]# lvdisplay /dev/vg01/lv01_snap0112_2159 --- Logical volume --- LV Name /dev/vg01/lv01_snap0112_2159 VG Name vg01 LV Write Access read only LV snapshot status active destination for /dev/vg01/lv01 LV Status available LV # 2 # open 1 LV Size 540.88 GB Current LE 8654 Allocated LE 8654 snapshot chunk size 64 KB Allocated to snapshot 0.00% [0/127.88 MB] Allocated to COW-table 128 KB Allocation next free Read ahead sectors 1024 Block device 58:1 [root@storageone root]# dd if=/dev/zero of=/vg01/lv01/SOMEFILE bs=1024k count=64 64+0 records in 64+0 records out [root@storageone root]# sync [root@storageone root]# lvdisplay /dev/vg01/lv01_snap0112_2159 --- Logical volume --- LV Name /dev/vg01/lv01_snap0112_2159 VG Name vg01 LV Write Access read only LV snapshot status active destination for /dev/vg01/lv01 LV Status available LV # 2 # open 1 LV Size 540.88 GB Current LE 8654 Allocated LE 8654 snapshot chunk size 64 KB Allocated to snapshot 50.15% [64.12 MB/127.88 MB] Allocated to COW-table 128 KB Allocation next free Read ahead sectors 1024 Block device 58:1 [root@storageone root]# lvextend -L+127M /dev/vg01/lv01_snap0112_2159 lvextend -- rounding relative size up to physical extent boundary lvextend -- extending logical volume "/dev/vg01/lv01_snap0112_2159" to 256 MB lvextend -- doing automatic backup of volume group "vg01" lvextend -- logical volume "/dev/vg01/lv01_snap0112_2159" successfully extended [root@storageone root]# df -k Filesystem 1K-blocks Used Available Use% Mounted on /dev/sda1 5903668 1476624 4427044 26% / /dev/vg01/lv01 567079312 67736 567011576 1% /vg01/lv01 /dev/vg01/lv01_snap0112_2159 567079312 2200 567077112 1% /snap/lv01_snap0112_2159 [root@storageone root]# umount /snap/lv01_snap0112_2159/ [root@storageone root]# mount /snap/lv01_snap0112_2159/ mount: wrong fs type, bad option, bad superblock on /dev/vg01/lv01_snap0112_2159, or too many mounted file systems [root@storageone root]# cat /etc/fstab /dev/sda1 / reiserfs defaults 0 0 /dev/sda2 swap swap defaults 0 0 /dev/vg01/lv01 /vg01/lv01 xfs defaults,usrquota,grpquota,noatime 0 0 /dev/vg01/lv01_snap0112_2159 /snap/lv01_snap0112_2159 xfs ro,nouuid,usrquota,grpquota,noatime 0 0 none /proc proc defaults 0 0 none /dev/pts devpts mode=622 0 0 ------------- The reasone that I did 'unmount' is to simulate the 'rebooting'. Because after rebooting, I can not mount the extended snapshot anymore. Thanks in advance ----- Original Message ----- From: <jon+lvm@silicide.dk> To: <linux-lvm@sistina.com> Sent: Sunday, January 12, 2003 10:09 PM Subject: Re: [linux-lvm] [Q] LVM snapshot volume extendable? > On Sun, Jan 12, 2003 at 09:12:07PM +0900, Sean Oh wrote: > > Hi > > > > I am using LVM 1.0.6, kernel 2.4.20 and XFS (from linux-2.4-xfs CVS). > > > > My question is that is the snapshot volume extendable? > > yes, just use lvextend. > > > > My environment is as follows: > > > > /dev/vg01/lv01 ---> XFS, 2G > > /dev/vg01/lv01_snap --> 256M, snapshot for /dev/vg01/lv01, mounted under > > /snap with ro,nouuid,usrquota,grpquota,noatime > > > > Now I have wrote a small shell scripts that if lv01_snap is more than 50% > > full, automatically increase the lv01_snap. But it seems to me that it does > > not work well.. > > I wrote one too, but rather than 50% used, i used XX MB free space. > > > > What I did in the shell scripts are 'lvextend -L+256M /dev/vg01/lv01_snap' > > with/without 'xfs_growfs /snap'. > > you dont need to grow the filesystem on the snapshot. > > > > After umounting the /snap and trying to remount /snap, it complaints as > > below > > you dont need to unmount it > > > > A LVM snapshot works by allocating a new "PE table". This means. > (# is allocated, - is not, and | is the end) > > LV: |-#################--##---#####-| > snapshot: |---| > > so, you change something in the LV > > LV: |-#############+###--##---#####-| > snapshot: |#--| > > Only the block that is actualy changed is moved to the snapshot. > If you need alot of changes your snapshot should be big, if you dont > change alot, you can use a much smaller snapshot. > > > > > > JonB > > _______________________________________________ > linux-lvm mailing list > linux-lvm@sistina.com > http://lists.sistina.com/mailman/listinfo/linux-lvm > read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/ > ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [linux-lvm] [Q] LVM snapshot volume extendable? 2003-01-12 7:29 ` Sean Oh @ 2003-01-12 11:16 ` jon+lvm 2003-01-12 22:37 ` Sean Oh 0 siblings, 1 reply; 6+ messages in thread From: jon+lvm @ 2003-01-12 11:16 UTC (permalink / raw) To: linux-lvm On Sun, Jan 12, 2003 at 10:29:54PM +0900, Sean Oh wrote: [cut] Would you be so kind to reply inbetween the text, as i did, or below (if it's not that much text) and while you are at it, cut the unneeeded lines out. You left all my text intact, which was 70 useless lines. JonB ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [linux-lvm] [Q] LVM snapshot volume extendable? 2003-01-12 11:16 ` jon+lvm @ 2003-01-12 22:37 ` Sean Oh 0 siblings, 0 replies; 6+ messages in thread From: Sean Oh @ 2003-01-12 22:37 UTC (permalink / raw) To: jon+lvm; +Cc: linux-lvm Sorry about the long text. Could you please tell me what kind of LVM version, kernel version, File System you are using for the extendabe snapshot? Do I need to apply writeable snapshot patch to have snapshot extendable? If so, Where can I get the patch for kernel 2.4.20? I have applied VFS-lock patch, lvm-0.8final-2.4.0.patch that comes with 1.0.6 distribution. Thanks in advance ^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2003-01-12 22:37 UTC | newest] Thread overview: 6+ messages (download: mbox.gz follow: Atom feed -- links below jump to the message on this page -- 2003-01-12 6:11 [linux-lvm] [Q] LVM snapshot volume extendable? Sean Oh 2003-01-12 7:09 ` Alasdair G Kergon 2003-01-12 7:09 ` jon+lvm 2003-01-12 7:29 ` Sean Oh 2003-01-12 11:16 ` jon+lvm 2003-01-12 22:37 ` Sean Oh
This is an external index of several public inboxes, see mirroring instructions on how to clone and mirror all data and code used by this external index.