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Re: Working whit snapshot file systems

 
Joell
Occasional Contributor

Working whit snapshot file systems

Hello!

I'm have a HP9000/N4000 server whit HP-UX 11.0 and I'm using a vxfs file systems and online JFS and I'm using a SNAPSHOT file systems for backup my data base, tha size of te file system for the D.B. is 14 gb. and the size of the lvol for the snapshot is 2.2 gb.

The problem is that the snapshot file system have errors, the errors apear when I type the command DMESG, the message are:

vxfs: mesg 028: vx_snap_alloc - /dev/vg01/lvol10 file system out of space
vxfs: mesg 032: vx_disable - /dev/vg01/lvol10 snapshot file system disable

And when I try to use the command BDF apear an I/O error and the file sistem is not mount, the question is: what can I do to solve this problem??

Tnks.
4 REPLIES 4
Devbinder Singh Marway
Valued Contributor

Re: Working whit snapshot file systems

Hi joell,

Have a look at the following link:-
http://europe-support.external.hp.com/cki/bin/doc.pl/sid=3efc2d040b455eb41b/screen=ckiSearchResults

basically it says :-
Message: 028 WARNING: msgcnt x: vxfs: mesg 028: vx_snap_alloc - mount_point snapshot file system out of space Explanation The snapshot file system ran out of space to store changes. During a snapshot backup, as the primary file system is modified, the original data is copied to the snapshot file system. This error can occur if the snapshot file system is left mounted by mistake, if the snapshot file system was given too little disk space, or the primary file system had an unexpected burst of activity. The snapshot file system is disabled.

Action

Make sure the snapshot file system was given the correct amount of space. If it was, determine the activity level on the primary file system. If the primary file system was unusually busy, rerun the backup. If the primary file system is no busier than normal, move the backup to a time when the primary file system is relatively idle or increase the amount of disk space allocated to the snapshot file system. Rerun any backups that failed when the error occurred.

Message: 032 WARNING: msgcnt x: vxfs: mesg 032: vx_disable - mount_point snapshot file system disabled Explanation Snapshot file system disabled, preceded by a message that specifies the reason.
Action

Unmount the snapshot file system, correct the problem specified by the message, and rerun any backups that failed due to the error.



Seek and you shall find
Rainer_1
Honored Contributor

Re: Working whit snapshot file systems

possibly your lvol for the snapshot fs is too small.
try increasing it.
John Waller
Esteemed Contributor

Re: Working whit snapshot file systems

About a year ago I went through a similar excersise and I was told that the snapshot file system needs to be large enough to hold any changed files not just the changed data within the file. If you have 2 Gb single file which gets changed you need 2Gb available on your snap shot lv. Also on a seperate note , don't expect to be able to use fbackup to backup the data , a snapshot file system is read only and fbackup tries to write a mark to the file when it is backed up which it can't perform.
Bill McNAMARA_1
Honored Contributor

Re: Working whit snapshot file systems

A snapshot immediately on creation, a bdf
will report the same size as the original.
Don't rely on bdf.
The snapshot size chosen should depend on
a> size of original
b> time to complete backup
c> amount of modification to original
during backup time.
A snapshot is not a 'real' filesystem morelike
it points to the files in your original filesystem that have NOT modified during the
backup process. The files that HAVE modified
in your original filesystem during the backup
will be copied to your snap filesystem so that
you have a true to time backup.

The only files in your snap filesystem are
those files modified during the backup.
If all files change during the backup window
your snaplv needs to be as big as the original
lv. Make sure that you are not leaving your
snap lv mounted/configured after completing
the backup.
use lvremove to get rid of it when your backup
has sucessfully completed. Otherwise choose
a greater lvsnap size to avoid any problem.

Hope this helps,
Bill
It works for me (tm)