Date: Tue, 15 Jan 2019 22:49:04 +0000 From: Matthew Seaman <matthew@FreeBSD.org> To: freebsd-questions@freebsd.org Subject: Re: ZFS for raid Message-ID: <169b6da2-167b-929a-2cb3-33a80f58e185@FreeBSD.org> In-Reply-To: <C14417F519F44EC85540C618@Pauls-MacBook-Pro.local> References: <C14417F519F44EC85540C618@Pauls-MacBook-Pro.local>
next in thread | previous in thread | raw e-mail | index | archive | help
This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --QQEx6UNNcXXEJlrG86AhlflQO4L2XZH2n Content-Type: multipart/mixed; boundary="AbXobJcHJYQ3isWgwHguw5MgfLa0xbxRR"; protected-headers="v1" From: Matthew Seaman <matthew@FreeBSD.org> To: freebsd-questions@freebsd.org Message-ID: <169b6da2-167b-929a-2cb3-33a80f58e185@FreeBSD.org> Subject: Re: ZFS for raid References: <C14417F519F44EC85540C618@Pauls-MacBook-Pro.local> In-Reply-To: <C14417F519F44EC85540C618@Pauls-MacBook-Pro.local> --AbXobJcHJYQ3isWgwHguw5MgfLa0xbxRR Content-Type: text/plain; charset=utf-8 Content-Language: en-GB Content-Transfer-Encoding: quoted-printable On 15/01/2019 21:48, Paul Schmehl wrote: > If you're going to setup drives with zfs for raid, do you need a > hardware controller? My impression is that you don't, but I want to kno= w > for sure before I order a server. ZFS provides all the functionality you'ld otherwise get from a RAID controller. What you need hardware-wize depends on how many drives you need to manage. If it's just a few then you might be able to use the SATA headers on your motherboard. If it's many drives then what you need is a Host Bus Adapter (or several) -- if you're undecided about ZFS and want the option of switching to a RAID card, there are some RAID cards can be reflashed as HBAs and vice-versa. Although generally the experience with ZFS is that it beats out HW RAID pretty much across the board. Some RAID controllers have a pass-through mode which effectively presents the individual drives to the OS. This isn't a bad choice. If you're stuck with a RAID controller with no possibility of reflashing or pass-through mode, but you really want ZFS, then it is possible to make each drive into a single-disk RAID array and manage those via ZFS, but this is non-ideal. ZFS works best when it has maximum access to each of the individual disks, and single-disk RAIDs interfere with that. What you certainly do need with ZFS is plenty of RAM, as ZFS makes extensive use of RAM for caching or bufferring disk IO. Somewhat counter-intuitively though best performance results are often obtained by limiting the amount of your RAM that ZFS can monopolise, since that leaves more memory available to your application software. > If there's no raid controller, can you setup raid using zfs during the > OS install? If you boot from the cd/dvd, do you get the option to > configure raid using zfs? Sure. The installer lets you allocate disks to your zpool, and create various types of mirroring, striping, raidz, raidz2, etc. ZFS is pretty forgiving, and it is possible to do quite radical surgery directly on the zpool you're booted from without needing to reboot the OS. Cheers, Matthew --AbXobJcHJYQ3isWgwHguw5MgfLa0xbxRR-- --QQEx6UNNcXXEJlrG86AhlflQO4L2XZH2n Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- iQKTBAEBCgB9FiEEGfFU7L8RLlBUTj8wAFE/EOCp5OcFAlw+Y2FfFIAAAAAALgAo aXNzdWVyLWZwckBub3RhdGlvbnMub3BlbnBncC5maWZ0aGhvcnNlbWFuLm5ldDE5 RjE1NEVDQkYxMTJFNTA1NDRFM0YzMDAwNTEzRjEwRTBBOUU0RTcACgkQAFE/EOCp 5OdK/xAAhxi8Xc+Ov2Q4XoOGImI3RLyWikOngd5O3Dahyxr3oHhH/sJM32f1r8gw bo/INzGLmoxFgHxx+4cXAbgXeR8wgqqAaZyIzK+ajj9ToEzu3IzbPqbU95YSExHZ rGVDOMYPxud1cW8SOjyUGLAWtyYsd7C/HPnudggAkmf/l6gkIgbdMG0LpaPNdovX Ty3U90Uy+0MRZv1cPrOnzVBQ2b/5sSyV6gF5RjpJKpWzZbFcYJFdMlzp8mxvGpZd DT+SAsUp6FE9czk8s0hibEER+n5GLb88SdHiKCQZ3F9rCxVEtxzdEE0F7Mc4kFzs ahr6VNHLhfOy47I1L0mvfVLgjn5mv0x2zI8a3z4MgkLptonguH7TKlSNRyrGQE9M JJxuSq/Ztffnv8a9x9V7vT+aAs5wBtyIImpnk8CaeMtgSLRX0uaRGImZJ3ALkUBq JEMgejYP4MVoAOBxqfxaVQujUGoCy94xVkk63BybX8Hr/sCjWyH0FoWnirYo3iZk CQAaoMaLTmkJixowj6LxLDOdTbhUyM+SUE0FI1YUDALhnt772G7qjFv0/WG4rFAv pkW0UaUYCFygSL65mndo6te5qQk0RR3x6f4J1eSOJOmRLjAvBdXcjOnf4ZYkEfen XvD89cfY5YopvyjZTHZh1cSEpBeHnuJPKana/fvMKz9tQyKyZh8= =TVH5 -----END PGP SIGNATURE----- --QQEx6UNNcXXEJlrG86AhlflQO4L2XZH2n--
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?169b6da2-167b-929a-2cb3-33a80f58e185>