Date: Sun, 20 Jan 2019 12:15:26 -0800 From: Freddie Cash <fjwcash@gmail.com> To: jdelisle <jdelisle@gmail.com> Cc: andy thomas <andy@time-domain.co.uk>, FreeBSD Filesystems <freebsd-fs@freebsd.org> Subject: Re: ZFS on Hardware RAID Message-ID: <CAOjFWZ7HtQ7f8t%2BR32OTGF5md_gd4KXT6fxt5ZUOQG5t6Sa9WQ@mail.gmail.com> In-Reply-To: <CAMdBLfQvF7mXriwAvu-h5BaXBNhb_8VPRRfDmeM0u1NGoyWY_g@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> <alpine.BSF.2.21.1901200930550.12592@mail0.time-domain.co.uk> <CAMdBLfQvF7mXriwAvu-h5BaXBNhb_8VPRRfDmeM0u1NGoyWY_g@mail.gmail.com>
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On Sun, Jan 20, 2019, 12:09 PM jdelisle <jdelisle@gmail.com wrote: > On Sun, Jan 20, 2019 at 9:04 AM andy thomas <andy@time-domain.co.uk> > wrote: > > > I don't h/w RAID controllers do any parity checking, etc for RAID 0 > > virtual disks containing only one disk? > > > > I can say for certain that with Dell PERC 6/e RAID (SAS 8087ELP based) > cards, when the virtual devices are entire disks each in a RAID0 > configuration, the way the adapter writes data to them is effectively the > same as JBOD. You can take a RAID0 drive from a PERC 6/e controller and > use in with an HBA/ "IT Mode" JBOD controller without issue. I personally > migrated 14x 1TB drives off PERC 6/e (all RAID0's) to a SAS 6gbps HBA, and > my ZFS VDEV's and pools were totally fine. You can move back and forth no > problem. I can't say this is the case for ALL RAID controllers, I've only > done this with an old PERC 6/e. 3Ware controllers configured for Single Disk arrays (which is different from JBOD mode) work the same way. You can move a disk from a Single Disk setup to a software RAID (mdadm or ZFS) without issue. We've migrated many Linux and FreeBSD systems from 3Ware to HBA to onboard SATA at work. I believe the difference between Single and JBOD on the 3Ware is the former allows the onboard cache to be used. Cheers, Freddie Typos due to smartphone keyboard.
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