Your TL;DR: for ashift refers to ZFS record size, but ashift determines block size (smallest I/O, with 12 meaning 4096 bytes to match common modern hard drive sector size), not record size.
Robert Trevellyan On Thu, Sep 12, 2019 at 8:22 AM Alwyn Kik <al...@proteon.com> wrote: > I did some research for this a while ago, and currently use the following > setup: https://gist.github.com/Alveel/c8e80aeef208a7e27c9bd50d0023420c > > Of course this is still far from perfect, and I welcome more ideas or > criticism, but perhaps it can help you out :) > > On 9/11/19 10:03 PM, Carl Soderstrom wrote: > > On 09/11 09:40 , Alexander Moisseev via BackupPC-users wrote: > > On 11.09.2019 18:19, Robert Trevellyan wrote: > > I'm letting ZFS do the compression (using the default of LZ4) with BackupPC > handling deduplication. I think you'll find a reasonable consensus that ZFS > compression is always a win for storage space (it will store un-compressible > data unmodified), whereas ZFS deduplication is best avoided in most cases, > mostly due to its high memory usage. It's possible that BackupPC compression > would be tighter than LZ4, > > Actually, on ZFS you are not limited to LZ4, but in ZFS each file block is > compressed independently, that is why in most cases BackupPC compression is > higher, though it depends on data. > > We moved from 77.96G cpool to pool on compressed filesystem recently. Now it > consumes 81.2G, so there is not much difference. > > # zfs get compression,compressratio,recordsize,referenced zroot/bpc/pool > NAME PROPERTY VALUE SOURCE > zroot/bpc/pool compression gzip-3 local > zroot/bpc/pool compressratio 3.87x - > zroot/bpc/pool recordsize 128K default > zroot/bpc/pool referenced 81,2G - > > Thanks Alexander, those details are really helpful. > > > -- > Alwyn > > _______________________________________________ > BackupPC-users mailing list > BackupPC-users@lists.sourceforge.net > List: https://lists.sourceforge.net/lists/listinfo/backuppc-users > Wiki: http://backuppc.wiki.sourceforge.net > Project: http://backuppc.sourceforge.net/ >
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