On Jun 26, 2018, at 14:21, Steve Barnet <[email protected]> wrote: > > 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. :-)
No, there is nothing wrong with the system. --- Andreas Dilger Principal Lustre Architect Whamcloud
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