On 1/28/12 8:55 AM, Martin Steigerwald wrote: > Am Freitag, 27. Januar 2012 schrieb Eric Sandeen: >> On 1/27/12 1:50 AM, Manny wrote: >>> Hi there, >>> >>> I'm not sure if this is intended behavior, but I was a bit stumped >>> when I formatted a 30TB volume (12x3TB minus 2x3TB for parity in RAID >>> 6) with XFS and noticed that there were only 22 TB left. I just >>> called mkfs.xfs with default parameters - except for swith and sunit >>> which match the RAID setup. >>> >>> Is it normal that I lost 8TB just for the file system? That's almost >>> 30% of the volume. Should I set the block size higher? Or should I >>> increase the number of allocation groups? Would that make a >>> difference? Whats the preferred method for handling such large >>> volumes? >> >> If it was 12x3TB I imagine you're confusing TB with TiB, so >> perhaps your 30T is really only 27TiB to start with. >> >> Anyway, fs metadata should not eat much space: >> >> # mkfs.xfs -dfile,name=fsfile,size=30t >> # ls -lh fsfile >> -rw-r--r-- 1 root root 30T Jan 27 12:18 fsfile >> # mount -o loop fsfile mnt/ >> # df -h mnt >> Filesystem Size Used Avail Use% Mounted on >> /tmp/fsfile 30T 5.0M 30T 1% /tmp/mnt >> >> So Christoph's question was a good one; where are you getting >> your sizes? To solve your original problem, can you answer the above question? Adding your actual raid config output (/proc/mdstat maybe) would help too. > An academic question: > > Why is it that I get > > merkaba:/tmp> mkfs.xfs -dfile,name=fsfile,size=30t > meta-data=fsfile isize=256 agcount=30, agsize=268435455 > blks > = sectsz=512 attr=2, projid32bit=0 > data = bsize=4096 blocks=8053063650, imaxpct=5 > = sunit=0 swidth=0 blks > naming =version 2 bsize=4096 ascii-ci=0 > log =Internes Protokoll bsize=4096 blocks=521728, version=2 > = sectsz=512 sunit=0 blks, lazy-count=1 > realtime =keine extsz=4096 blocks=0, rtextents=0 > > merkaba:/tmp> mount -o loop fsfile /mnt/zeit > merkaba:/tmp> df -hT /mnt/zeit > Dateisystem Typ Größe Benutzt Verf. Verw% Eingehängt auf > /dev/loop0 xfs 30T 33M 30T 1% /mnt/zeit > merkaba:/tmp> LANG=C df -hT /mnt/zeit > Filesystem Type Size Used Avail Use% Mounted on > /dev/loop0 xfs 30T 33M 30T 1% /mnt/zeit > > > 33MiB used on first mount instead of 5? Not sure offhand, differences in xfsprogs version mkfs defaults perhaps. ... > Hmmm, but creating the file on Ext4 does not work: ext4 is not designed to handle very large files, so anything above 16T will fail. > fallocate instead of sparse file? no, you just ran into file offset limits on ext4. > And on BTRFS as well as XFS it appears to try to create a 30T file for > real, i.e. by writing data - I stopped it before it could do too much > harm. Why do you say that it appears to create a 30T file for real? It should not... > Where did you create that hugish XFS file? On XFS. Of course. :) > Ciao, _______________________________________________ xfs mailing list xfs@xxxxxxxxxxx http://oss.sgi.com/mailman/listinfo/xfs
