Reduce /var filesystem

UNIX for Beginners Q & A UNIX for Dummies Questions & Answers
1

hi guys

I need to create a temporary Filesystem and the only way to do it is to reduce /var and create a new filesystem 3GB size

df -h
....
...
/dev/mapper/VolGroup00-var
                      9.7G  1.5G  7.8G  16% /var

my question is according to google search I need to umount the filesystem point in order to reduce its size.... so it means I will require that nobody uses the system? since /var logs a lot information?

I also have the option to reduce /root but I think is more complicated.

so what are the precautions in order to reduce /var/?

thanks a lot

2

There will be a lot of demons writing in there - I suggest you boot up this box with same rescue disc or in safe mode and try to umount /var and reduce it according to your LVM commands. Anyway your /var looks veeeery large, maybe far too large.
Maybe there is another less important FS in your VG that can be unmounted and reduced only.. maybe something like /home, idk.

3

We assume that you do not have 3 Gb of unallocated disc space and cannot add new discs.

Personally I wouldn't attempt to reduce a filesystem "in situ". I believe that it is only ever safe to create a replacement filesystem. This is because it can be too difficult to find out the high water mark of a filesystem even where your O/S allows you to re-size filesystems and disc partitions.

If you embark on this, make two "cold metal" backups (I don't mean "tar") of all system partitions (incl. /var) and rehearse recovery on a spare computer before rehearsing the operation on that spare computer.

It may be easier to create soft link under root (or whatever) with the required name of the temporary filesystem and point it to a new directory under /var .

4

just something like this

ln -s /var/newfs NewFileSystem

?

5

If you want to provide space to this server on temporary basis then :

1) You can take space from any other server.
2) Make a filesystem on that server.
3) NFS mount this filesystem on to your required server.

:b::b:

6 
ln -s /var/newfs NewFileSystem

Yes.

Of course it isn't actually a filesystem, you are just using disc space under /var .

Depending on the circumstances you could just create a directory under /var .