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Software RAID - where is all my space?

Hi All,

I have used mdadm to set up a RAID5 system using 3x500GB drives.

Code:

~# cat /proc/mdstat 

Personalities : [raid6] [raid5] [raid4] 

md0 : active raid5 hdd1[2] hdc1[1] hdb1[0]

      976767872 blocks level 5, 64k chunk, algorithm 2 [3/3] [UUU]

      

unused devices: <none>

Upon creating an etx3 filesystem and mounting, I see that I have about 50 GB missing from the filesystem!

Code:

/share# df -h

Filesystem            Size  Used Avail Use% Mounted on

/dev/hda1            3.8G  573M  3.0G  16% /

varrun                62M  48K  62M  1% /var/run

varlock                62M    0  62M  0% /var/lock

procbususb            62M  76K  62M  1% /proc/bus/usb

udev                  62M  76K  62M  1% /dev

devshm                62M    0  62M  0% /dev/shm

/dev/md0              917G  200M  871G  1% /share



/share# ls -lah

total 24K

drwxr-xr-x  3 root root 4.0K 2007-08-30 10:35 .

drwxr-xr-x 22 root root 4.0K 2007-08-30 10:38 ..

drwx------  2 root root  16K 2007-08-30 10:35 lost+found

Note that the fs is currently completely empty. Where has the extra space gone??

The ext3 filesystem reserves approximately 3% of available space for system use. That 3% doesn't show up as available, therefore it appears that you have missing disk space.

Note that 3% of 3x500 gig comes out to 45 gig.

Ah Yes that was it. I knew that ext3 reserved some space but I never thought it to be such a large volume. Using tune2fs to change reserved blocks to 1% has made a difference.

Thanks. :D