Claus Guttesen writes: > > So the 1 MB files are stored as ~8 x 128K recordsize. > > > > Because of > > 5003563 use smaller "tail block" for last block of object > > > > The last block of you file is partially used. It will depend > > on your filesize distribution by without that info we can > > only guess that we're wasting an avg of 64K per file. Or 6%. > > > > If your distribution is such that most files are slightly > > more than 1M, then we'd have 12% overhead from this effect. > > > > So using 16K/32K recordsize would quite possibly help as > > files would be stored using ~ 64 x 16K blocks with an > > overhead of < 1-2% (0.5 blocks wasted every 64). > > I will (re)create the partition and modify the recordsize. I was > unwilling to do so when I read the man page which discourages > modifying this setting unless a database was used. > > Does zfs use suballocation if a file does not use an entire > recordsize? If not the thumbnails probably wastes most space. They are > approx. 4 KB. >
Files smaller than 'recordsize' are stored using a multiple of the sector size. So small files should not factor in this equation. > I'll be testing recordsizes from 1K and upwards. Actually 1K made zfs > very slow but 2K seems fine. I'll report back when the entire > partition has been copied. When I find the sweet spot I'll try to > enable (default) compression. Beware because at 2K you might be generating more indirect blocks. For 1MB files the gains from using a recordsize smaller than 16K start to be quite small. -r > > Thank you. > > -- > regards > Claus > > When lenity and cruelty play for a kingdom, > the gentlest gamester is the soonest winner. > > Shakespeare _______________________________________________ zfs-discuss mailing list [email protected] http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
