Date: Sun, 20 Jan 2019 16:41:07 +0100 From: Ben RUBSON <ben.rubson@gmail.com> To: freebsd-fs <freebsd-fs@freebsd.org> Subject: Re: ZFS on Hardware RAID Message-ID: <7C7F0DBB-C751-433A-BCB7-4EBE71BB821D@gmail.com> In-Reply-To: <CAOeNLuqQDJ3O1DgzdkshhiJVXd=6aPCMn86BOSwsJLZRdz21aw@mail.gmail.com> References: <1180280695.63420.1547910313494.JavaMail.zimbra@gausus.net> <92646202.63422.1547910433715.JavaMail.zimbra@gausus.net> <CAOeNLurgn-ep1e=Lq9kgxXK%2By5xqq4ULnudKZAbye59Ys7q96Q@mail.gmail.com> <alpine.BSF.2.21.1901200834470.12592@mail0.time-domain.co.uk> <1691666278.63816.1547976245836.JavaMail.zimbra@gausus.net> <CAOeNLuqQDJ3O1DgzdkshhiJVXd=6aPCMn86BOSwsJLZRdz21aw@mail.gmail.com>
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The only thing I would try with a HW RAID card is to configure one = volume per physical disk, so that ZFS can operate as intended. Well, more or less, as there will still be some components in the path = which should not be expected, such as the RAID card cache (you have ZFS = ZIL & ARC / LARC2, upcoming allocation classes). Thus, an IT-mode HBA, for some dozens of dollars / euros, is really = worth the price ! ZFS does not really make sense with only one disk (what's the checksum = benefit once it has failed ?), you could go with any other FS... Regarding cache, be sure you can rely on your disks, as some = (budget-ones ?) may lie answering data is on disk whereas it has only = reached their write cache. You can toggle write cache depending on your disks. camcontrol mode /dev/<disk> -m8 | grep WCE Regarding CPU usage, I'm pretty sure all checksum operations are well = hardware-supported, CPU should not be a bottleneck here (disks will = first be). Ben
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