On Donnerstag, 21. Juli 2011 Dave Chinner wrote: > No, they'll get sunit aligned but default, which would be on 64k > boundaries. OK, so only when <quote Dave> "swalloc mount option set and the allocation is for more than a swidth of space it will align to swidth rather than sunit" </quote Dave>. So even when I specify swalloc but a file is generated with only 4KB, it will very probably be sunit aligned on disk. > > That way, all stripes of a 1GB partition would be full when > > there are roughly 1170 files (1170*896KiB ~ 1GB). What would happen > > when I create other files - is XFS "full" then, or would it start > > using sub- stripes? If sub-stripes, would they start at su > > (=64KiB) distances, or at single block (e.g. 4KiB) distances? > > It starts packing files tightly into remaining free space when no > free aligned extents are availble for allocation in the AG. That means for above example, that 16384 x 2KiB files could be created, and each be sunit aligned on disk. Then all sunit start blocks are full, so additional files will be sub-sunit "packed", is it this? That would mean fragmentation is likely to occur from that moment, if there are files that grow. And files >64KiB are immediately fragmented then. At this time, there are only 16384 * 2KiB = 32MiB used, which is 3,125% of the disk. I can't believe my numbers, are they true? OK, this is a worst case scenario, and as you've said before, any filesystem can be considered full at 85% fill grade. But it's incredible how quickly you could fuck up a filesystem when using su/sw and writing small files. -- mit freundlichen Grüssen, Michael Monnerie, Ing. BSc it-management Internet Services: Protéger http://proteger.at [gesprochen: Prot-e-schee] Tel: +43 660 / 415 6531 // Haus zu verkaufen: http://zmi.at/langegg/
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