On Sun, Jan 09, 2011 at 12:52:56PM +0100, Attila Nagy wrote: [...] > I've finally found the time to read the v28 patch and figured out the > problem: vfs.zfs.l2arc_noprefetch was changed to 1, so it doesn't use > the prefetched data on the L2ARC devices. > This is a major hit in my case. Enabling this again restored the > previous hit rates and lowered the load on the hard disks significantly.
Well, not storing prefetched data on L2ARC vdevs is the default is Solaris. For some reason it was changed by kmacy@ in r205231. Not sure why and we can't ask him now, I'm afraid. I just sent an e-mail to Brendan Gregg from Oracle who originally implemented L2ARC in ZFS why this is turned off by default. Once I get answer we can think about turning it on again. -- Pawel Jakub Dawidek http://www.wheelsystems.com p...@freebsd.org http://www.FreeBSD.org FreeBSD committer Am I Evil? Yes, I Am!
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