[lustre-discuss] MDT size smaller than expected

[Steve Barnet]

Hi all,

   I'm setting up a new lustre filesystem with 2.10.4. Things are
looking OK so far. However, I noticed that when I mount up
my MDT, df reports a smaller size than I expect. The volume is
2.2TB, but the MDT reports 1.3:


icecube-lfs6-mds-1 ~ # df -h -t lustre
Filesystem                 Size  Used Avail Use% Mounted on
/dev/mapper/md3420-1-vd-0  1.3T   94M  1.2T   1% /mnt/lustre/lfs6-mdt0000


It appears that the host sees the correct size for the volume:

icecube-lfs6-mds-1 ~ # fdisk -l /dev/mapper/md3420-1-vd-0

Disk /dev/mapper/md3420-1-vd-0: 2388.7 GB, 2388672905216 bytes, 
4665376768 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes


   So I am a little confused. Seems to work OK, but I'd like
to understand what might be going on there.

I've included the commands to create the MDT below.

Any ideas?

Thanks much!

Best,

---Steve


---------------------------------------------------------------------

mkfs.lustre --fsname=lfs6 --reformat --mgs --mdt 
--servicenode=lfs6-mds-1 at tcp1 --servicenode=lfs6-mds-2 at tcp1 --index=0 
/dev/mapper/md3420-1-vd-0 >> mkfs.out


icecube-lfs6-mds-1 ~ # cat mkfs.out

    Permanent disk data:
Target:     lfs6:MDT0000
Index:      0
Lustre FS:  lfs6
Mount type: ldiskfs
Flags:      0x1065
               (MDT MGS first_time update no_primnode )
Persistent mount opts: user_xattr,errors=remount-ro
Parameters:  failover.node=10.128.11.145 at tcp1:10.128.11.144 at tcp1

device size = 2278016MB
formatting backing filesystem ldiskfs on /dev/mapper/md3420-1-vd-0
	target name   lfs6:MDT0000
	4k blocks     583172096
	options        -J size=4096 -I 1024 -i 2560 -q -O 
dirdata,uninit_bg,^extents,mmp,dir_nlink,quota,huge_file,flex_bg -E 
lazy_journal_init -F
mkfs_cmd = mke2fs -j -b 4096 -L lfs6:MDT0000  -J size=4096 -I 1024 -i 
2560 -q -O 
dirdata,uninit_bg,^extents,mmp,dir_nlink,quota,huge_file,flex_bg -E 
lazy_journal_init -F /dev/mapper/md3420-1-vd-0 583172096
Writing CONFIGS/mountdata