RAID5 capacity

jovie · 06-14-2006, 06:14 AM

Hi

If I've got 4 x 250G hard drives on a RAID5 system shouldn't df -h report the size as somewhere close to 750G?

It's only showing 691G and I wonder if this was always the case or if I've lost some capacity during recient changes. The system hard drive failed (not part of the RAID) and the replacement has the OS upgraded from RH9 to FC4 with the RAID controller re-configured for the change.

I'm going to have a capacity problem anyway but those missing 59G would help if they were available. Should they be?

Thanks

Code:

Filesystem            Size  Used Avail Use% Mounted on
/dev/hda2              20G   18G  954M  95% /
/dev/hda1              99M   13M   82M  14% /boot
/dev/shm             1013M     0 1013M   0% /dev/shm
/dev/hda3             163G   64G   91G  42% /home
/dev/sda1             691G  624G   32G  96% /data

marozsas · 06-14-2006, 06:49 AM

There is 5% reserved on this filesystem as a safety resource for root user.
You can check yours with the command "tune2fs -l /dev/sda1" and inspecting the line "Reserved block count:". It should be 5% or 10% of "Block count:" value.

Other space is used by the filesystem itself, like superblocks, bad blocks maps, etc....

So, a really full filesystem should display 105% at Use% colunm.

Attention: The command tune2fs is fine for ext2/ext3 partition. If yours is reiserfs, xfs, or other, the command tune2fs will not work ! I don't know a similar program for theses others fs, but the concept is the same.

jovie · 06-14-2006, 07:08 AM

Thanks.

There is a 5% reserve which equates to 37.5G