Hi Andreas,
On 6/25/18 5:47 PM, Andreas Dilger wrote:
On Jun 25, 2018, at 20:39, Steve Barnet <[email protected]> wrote:
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.
About half of the MDT is consumed by the inodes with the default formatting
parameters,
so this won't ever show up as part of the free space in the filesystem. The
statfs()
interface is somewhat limited in what it can show, and the alternative is to
show the
total blocks as 2.2TB, but there is 1.1TB of "Used" space, which would probably
get
even more questions on the flip side "why is half of my MDT filesystem used,
and how
do I get rid of that space usage".
Thanks much. So just to make sure I'm clear when the
inevitable question arises: the total size is 2.2TB,
however, 1.1TB of that is inodes so that is subtracted
from the 2.2TB and that's what we see in df.
That makes sense, and I can definitely see why that
choice would be made. I just wanted to be sure I
hadn't done something I might regret for the life of
the filesystem. :-)
Thanks again!
Best,
---Steve
Cheers, Andreas
---------------------------------------------------------------------
mkfs.lustre --fsname=lfs6 --reformat --mgs --mdt --servicenode=lfs6-mds-1@tcp1
--servicenode=lfs6-mds-2@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@tcp1:10.128.11.144@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
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---
Andreas Dilger
Principal Lustre Architect
Whamcloud
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