Mucking with a mounted filesystem?

Kenny Lussier klussier at gmail.com
Thu Jul 9 16:53:37 EDT 2009


On Thu, Jul 9, 2009 at 4:45 PM, Bill McGonigle<bill at bfccomputing.com> wrote:
> On 07/09/2009 04:14 PM, Kenny Lussier wrote:
>> I am running into a disk space issue on an older server. I'd like to
>> do a tune2fs -m 1 (or maybe 0) to get rid of most, if not all of the
>> reserved block space on the partition that is close to full. The disk
>> is actually an iSCSI volume mounted from an EqualLogic array, and then
>> exported via NFS to 6 other servers.
>
> I think that kind of superblock info is only consulted at mount time, so
> probably nothing will notice if you do it, but you won't get any benefit
> until you mount again.
>
> Does '-o remount' consult the superblock or only process things that can
> be expressed as mount options?  The man page only says:
>
>  "all ext2fs-specific parameters, except sb,
>  are changeable with a remount"
>
> but 'sb' is one that has -o semantics.

It will work, and space gained without a remount (I was prompted to
try it on an unimportant system):


[root at L-kluss ~]# df -h /dev/sda1
Filesystem            Size  Used Avail Use% Mounted on
/dev/sda1              99M   80M   15M  85% /boot

[root at L-kluss ~]# tune2fs -m 0 /dev/sda1
tune2fs 1.35 (28-Feb-2004)
Setting reserved blocks percentage to 0 (0 blocks)

[root at L-kluss ~]# df -h /dev/sda1
Filesystem            Size  Used Avail Use% Mounted on
/dev/sda1              99M   80M   20M  81% /boot

I suppose the real question is whether it is safe to do it on a
filesystem that is exported. I'll look for another box and set up NFS,
I guess.

Thanks,
Kenny



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