Date: Wed, 6 Jan 2010 22:44:39 +0100 From: Anselm Strauss <amsibamsi@gmail.com> To: krad <kraduk@googlemail.com> Cc: freebsd-questions@freebsd.org Subject: Re: Booting from ZFS raidz Message-ID: <4284CE82-9BE5-463D-AEFC-299CA7347C7C@gmail.com> In-Reply-To: <d36406631001061237h2610029ahf2cc0e2dc944ddd5@mail.gmail.com> References: <15FCFBD0-9B68-421B-A99C-1038BAD61362@gmail.com> <d36406631001061237h2610029ahf2cc0e2dc944ddd5@mail.gmail.com>
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On Jan 6, 2010, at 21:37 , krad wrote: > 2010/1/6 Anselm Strauss <amsibamsi@gmail.com> > Hi, >=20 > I'm experimenting with a ZFS only system and booting from it in = VirtualBox. Thanks to various mails and forum posts from the net I have = a working scenario with booting from a ZFS mirror. However, I can't get = the thing to work with raidz with the exactly same setup, except that = the pool is now raidz instead of mirror and there is one more disk. I = feel sure I have all the stuff with partitioning, boot loader = installation, etc. right. I tested this with version 8.0-RELEASE on = 64bit. >=20 > Now, before I go into detailed explaining, is raidz really supported? = I always get the following error after it says "FreeBSD/i386 bootstrap = loader, Revision 1.1": >=20 > ZFS: i/o error - all block copies unavailable > ZFS: can't read MOS object directory > (repeats a lot) > Can't find root filesystem - giving up > can't load 'kernel' >=20 > I think the "MOS" message comes from zfs_mount_root() in = /usr/src/sys/boot/zfs/zfsimpl.c. I asume that is the point when = /boot/loader has been loaded and now wants to load the kernel into = memory. After that error I'm in the loader prompt. When I try to load = any file I always get the same error as above. >=20 > Anyone any ideas? >=20 > Thanks, > Anselm_______________________________________________ > freebsd-questions@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-questions > To unsubscribe, send any mail to = "freebsd-questions-unsubscribe@freebsd.org" >=20 > Opensolaris doesnt support booting off raidz yet so id be surprised if = you managed to, as i doubt all the relevent code is in the loader, and = robust enough yet. I have seen a few hacks mentioned in places that = might get it to work, bit these are unsupported and might flake out at = any time. >=20 > Also why do you need a raidz for the os? It implys you might be mixing = data on the pool as well. This isnt best practice, and you are best off = having a separate pool for os and data. If you have 3+ drives, gpt it = into 3 or 4 chunks dependent on whether you want swap on a zvol. Have = and x way mirror for the os and then the last and biggest gpt slice use = for your raidz data. Better still have the os and data on separate = spindles I was just out for maximum flexibility and easiness. Having just one = pool gives you the most possibilities in resizing data sets. Using = partitions always imposes some hard limits that are sometimes different = to overcome when you want to re-layout you filesystems. I like the idea = of ZFS that the boundaries between filesystems (or data sets) are just = quotas and reservations, instead of low-level address borders as with = partitions. But then again, as you mentioned, one might want to make = multiple pools for best performance. At least I want to have the system = data on a redundant volume, but you are right I could just make a = separate mirror for that. By the way, I also tested to boot from a degraded mirror, which worked = perfectly well. You just have to make sure that the boot loader stages = are installed on all drives. Thanks, Anselm
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