Paul Tice wrote: > I just bumped up the kmem, arc.max, enabled zil and reenabled > mdcomp. Prefetch is disabled. Less than 1 minute into a backup > run of only 4 machines, I've got a fresh ZFS wedgie. How exactly did you bump up kmem? As far as I know, it is not necessary anymore on 8-current/amd64, because the defaults are already much larger. In fact it might be possible that your tuning made things worse. > As I understand it, the ZIL is not as much of an integrity boost as > a speed boost, especially since we already have checksum-per-block. The checksum feature works purely on a block level, while the intent log (ZIL) records certain changes to meta data on the file system, similar to a journal, which can be used for recovery after a crash (power outage, hardware failure, kernel panic, human error). Both features are completely orthogonal, one cannot replace the other. Therefore I recommend to keep the ZIL enabled. Best regards Oliver -- Oliver Fromme, secnetix GmbH & Co. KG, Marktplatz 29, 85567 Grafing b. M. Handelsregister: Registergericht Muenchen, HRA 74606, Geschäftsfuehrung: secnetix Verwaltungsgesellsch. mbH, Handelsregister: Registergericht Mün- chen, HRB 125758, Geschäftsführer: Maik Bachmann, Olaf Erb, Ralf Gebhart FreeBSD-Dienstleistungen, -Produkte und mehr: http://www.secnetix.de/bsd "In My Egoistical Opinion, most people's C programs should be indented six feet downward and covered with dirt." -- Blair P. HoughtonReceived on Thu Jan 29 2009 - 13:48:57 UTC
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