Date: Sun, 26 Jun 2011 23:35:34 +0200 From: Wiktor Niesiobedzki <bsd@vink.pl> To: freebsd-fs@freebsd.org Subject: Re: ZFS L2ARC hit ratio Message-ID: <BANLkTi=G_W3V-M5_M3Vue%2BgYaA3TTHVwzQ@mail.gmail.com> In-Reply-To: <4E0435B6.30004@fsn.hu> References: <BANLkTinyveD7D=PYv3eqdxZb=KneKxg9Zg@mail.gmail.com> <4E0435B6.30004@fsn.hu>
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2011/6/24 Attila Nagy <bra@fsn.hu>: > On 06/21/11 21:59, Wiktor Niesiobedzki wrote: >> >> I've recently migrated my 8.2 box to recent stable: >> FreeBSD kadlubek.vink.pl 8.2-STABLE FreeBSD 8.2-STABLE #22: Tue Jun =C2= =A07 >> 03:43:29 CEST 2011 =C2=A0 =C2=A0 root@kadlubek:/usr/obj/usr/src/sys/KADL= UB =C2=A0i386 >> >> And upgraded my ZFS/ZPOOL to newest versions. Though through my >> monitoring I've noticed some declination in L2ARC hit ratio (server is >> not busy, so it doesn't look that suspicious). I've made some tests >> today and I guess, that there might be some problem: > > Likely because vfs.zfs.l2arc_noprefetch is now 1. > > I'm running on i386 so prefetch for me was always disabled. It turns out, that the "bad" behaviour is a result of putting: vfs.zfs.prefetch_disable=3D0 In loader.conf I thought that this is somehow better in ZFS v28, than in v15. Anyhow, it looks like prefetching shall be left disabled for now. Cheers, Wiktor Niesiobedzki
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