Date: Mon, 27 Apr 2015 11:08:32 -0500 From: Rick Romero <rick@havokmon.com> To: freebsd-fs <freebsd-fs@freebsd.org> Subject: 10.1 + ZFS snapshot eating diskspace Message-ID: <20150427110832.Horde.MAoPtcoic1-3sfV0OhkyxQ1@www.vfemail.net>
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Try number two. I built another new system, no encryption this time. I replacated ONE snapshot that is about 562GB of data. (I just found Ronalds reply in my Spam folder, sorry!) This new 10.1 system has the exact same 3 drives in RAIDZ1 as the original source (9.2). What's confusing is the original RAIDZ1 is replicated correctly to a 10 drive RAIDZ2 (10.1), but the RAIDZ2 source cannot replicate data correctly to a new 3 drive RAIDZ1. So not only is this a problem with the new system, but it concerns me that if there were a problem with the old system that a full restore from backup would eat all the disk space. Source: # zfs get all sysvol/primessd_home |grep -i used sysvol/primessd_home used 822G - sysvol/primessd_home usedbysnapshots 260G - sysvol/primessd_home usedbydataset 562G - sysvol/primessd_home usedbychildren 0 - sysvol/primessd_home usedbyrefreservation 0 - sysvol/primessd_home logicalused 811G - Right? 562 is the 'current' amount of space used? So I send it to a new box, and this is the result # zfs list -t all NAME USED AVAIL REFER MOUNTPOINT sysvol 919G 0 12.5G /sysvol sysvol/home 906G 0 898G /sysvol/home sysvol/home@remrep-Week16 8.53G - 898G - I can see a possible sector size diff or recordsize affecting a few bytes, but 400G is a bit excessive. The fact that it more closely matches the full dataset+snapshots, IMHO, is much more telling. # zfs get all sysvol/home | grep used sysvol/home used 906G - sysvol/home usedbysnapshots 8.53G - sysvol/home usedbydataset 898G - sysvol/home usedbychildren 0 - sysvol/home usedbyrefreservation 0 - sysvol/home logicalused 574G - logical used is actual used, correct? Why is it the 'full' amount, when only one snapshot was replicated? So I thought maybe it's not reporting correctly # zfs list NAME USED AVAIL REFER MOUNTPOINT sysvol 907G 12.3G 256M /sysvol sysvol/home 906G 12.3G 898G /sysvol/home # dd bs=1M count=12560 if=/dev/zero of=test2 dd: test2: No space left on device 12558+0 records in 12557+1 records out 13167886336 bytes transferred in 33.499157 secs (393081126 bytes/sec) # zfs list NAME USED AVAIL REFER MOUNTPOINT sysvol 919G 0 12.5G /sysvol sysvol/home 906G 0 898G /sysvol/home # dd bs=1M count=12560 if=/dev/zero of=test3 dd: test3: No space left on device So what's going on? Is this a known issue? I suppose I can take the new server down to the colo and replicate from the original, but that doesn't resolve the 'restore from backup' issue that I see happening...
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