Am Samstag, 9. März 2013 schrieb Pascal: > Hello, Hi Pascal, > I am asking you because I am insecure about the correct answer and > different sources give me different numbers. > > > My question is: What is the maximum file system size of XFS? > > The official page says: 2^63 = 9 x 10^18 = 9 exabytes > Source: http://oss.sgi.com/projects/xfs/ > > Wikipedia says 16 exabytes. > Source: https://en.wikipedia.org/wiki/XFS > > Another reference books says 8 exabytes (2^63). > > > Can anyone tell me and explain what is the maximum file system size for > XFS? You can test it. The theoretical limit. Whether such a filesystem will work nicely with a real workload is, as pointed out, a different question. 1) Use a big enough XFS filesystem (yes, it has to be XFS for anything else that can carry a exabyte big sparse file) merkaba:~> LANG=C mkfs.xfs -L justcrazy /dev/merkaba/zeit meta-data=/dev/merkaba/zeit isize=256 agcount=4, agsize=1310720 blks = sectsz=512 attr=2, projid32bit=0 data = bsize=4096 blocks=5242880, imaxpct=25 = sunit=0 swidth=0 blks naming =version 2 bsize=4096 ascii-ci=0 log =internal log bsize=4096 blocks=2560, version=2 = sectsz=512 sunit=0 blks, lazy-count=1 realtime =none extsz=4096 blocks=0, rtextents=0 2) Create a insanely big sparse file merkaba:~> truncate -s1E /mnt/zeit/evenmorecrazy.img merkaba:~> ls -lh /mnt/zeit/evenmorecrazy.img -rw-r--r-- 1 root root 1,0E Mär 11 22:37 /mnt/zeit/evenmorecrazy.img (No, this won´t work with Ext4.) 3) Make a XFS file system into it: merkaba:~> mkfs.xfs -L /mnt/zeit/evenmorecrazy.img I won´t today. I tried that for gag during a linux performance and analysis training I held on a ThinkPad T520 with Sandybridge i5 2,50 GhZ, Intel SSD 320 on an about 20 GiB XFS filesystem. The mkfs command run for something like one or two hours. It was using quite some CPU and quite some SSD, but did not max out one of it. The host XFS filesystem was almost full, so the image took just about those 20 GiB. 4) Mount it and enjoy the output of df -hT. 5) Write to if it you dare. I did it, until the Linux kernel told something about "lost buffer writes". What I found strange is, that the dd writing to the 1E filesystem did not quit then with input/output error. It just ran on. I didn´t test this with any larger size, but if size and time usage scales linearily it might be possible to create a 10EiB filesystem within 200 GiB host XFS and hum about a day of waiting :). No, I do not suggest to use anything even just remotely like this in production. And no, my test didn´t show that an 1EiB filesystem will work nicely with any real life workload. Am I crazy for trying this? I might be :) Thanks, -- Martin 'Helios' Steigerwald - http://www.Lichtvoll.de GPG: 03B0 0D6C 0040 0710 4AFA B82F 991B EAAC A599 84C7 _______________________________________________ xfs mailing list xfs@xxxxxxxxxxx http://oss.sgi.com/mailman/listinfo/xfs
