Descrease filesystem size

[Bruno Bossier_1]

What is the correct procedure to online descrease the size of a filesystem ? I thought :

1. Defragment filesystem : fsadm -E /mountpoint
2. lvreduce ....
3. fsadm -b b /mountpoint

Bruno

[Pete Randall]

Bruno,

If you shrink the container that holds the file system with lvreduce, you're going to lose data. If you do lvreduce (I can't remember) at all, it would have to be after the fsadm.


Pete

[Bruno Bossier_1]

OK, so I was wrong in the sequence :

1. fsadm -E /mountpoint
2. fsadm -b b /mountpoint
3. lvreduce ...

Correct ?

[Pete Randall]

Bruno,

Also check this post:

http://forums2.itrc.hp.com/service/forums/questionanswer.do?threadId=582409


Pete

[Pete Randall]

Bruno,

Yes, that's correct:

defrag
fsadm
lvreduce


Pete

[Robert-Jan Goossens]

Bruno,

Be on the save side. Create a copy on tape or if you have enough filestore, create a online tar/cpio archive before reducing the volume.

The commands are correct, but the last time I preformed this I got a corrupt filesystem.

Regards,
Robert-Jan

[Bruno Bossier_1]

I know it's tricky and to be on the safe side, I should backup, delete, recreate and restore. It's for a sapdata filesystem, so even more tricky.

I just wanted to check. I'm not sure whether I would really do it.

Thanks for the answers !

Cheers,
Bruno

[Geoff Wild]

I agree with Robert Jan - make sure your backups are working.

To be safe - I would reduce during your maintenance window - not during the day.

IE - during a backup - and to be safe - I would have SAP/Oracle down.

Rgds...Geoff

[Florian Heigl (new acc)]

In general I have good experience with fsadm and reducing filesystems, but I haven't tried it more than 10 times, as it's plain forbidden @work.

You should definitely check the filesystem version and fsadm patch levels before the fsadm call.
root@xxxx:/tmp>fstyp -v /dev/vg00/rlvol15
vxfs
version: 4

if this doesn't print out Version 4 or 5, You might want to think twice on a sapdata filesystem.

florian

[Roland Piette]

Hello Bruno,

If you decide to apply the procedure, don't do it with SAP running. Your DB will crash when reorganization is running !

Only a remark
Roland

[Matthew_50]

make a backup of your data before any changes

If you have OnlineJFS. do following steps.
1. fsadm -F vxfs -d -D -e -E /mountpoint
2. fsadm -F vxfs -b 4096000 /mountpoint
3. lvreduce -L 4096 /dev/vg00/lvol12

Note:
-b with new fs size in KB
-L with new fs size in MB

[Kevin Wright]

If your FS is an even multiple of the extents, it may work. OnlineJFS, although advertised that is can resize, grow and reduce, rarely works correctly on a reduce. As other said, ensure your apps aren't running, and get a solid backup before attempting to reduce.

[Bill Hassell]

You can safely assume that reducing a filesystem size will DESTROY data on your logical volume. Only if you are running 11.11 *AND* have purchased Online JFS version 3.3 *AND* the filesystem has been created or converted to version 4, will a reduction work. So in the majority of cases, your procedure will always be:

1. save all the files and directories (tape or another disk)

2. Un-mount the lvol

3. lvremove the lvol

4. Re-create the lvol in the size you want

5. newfs the lvol

6. mount the new filesystem

7. Restore your data

[Fabio Ettore]

Hi Bruno,

with the Online JFS product you can shrink the filesystem even if the filesystem is mounted.

Anyway it is the best thing to backup all data before because it always is dangerous to shrink. I remeber something about the filesystem version, you should have the 3.3 or 4 version as Bill and Florian pointed out.

The good order is

fsadm -E /
fsadm -b /M /
lvreduce -L /dev/vgXX/lvolX

Best regards,
Fabio

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