[zfs-discuss] Boot with/from ZFS
rlaager at wiktel.com
Sat Nov 24 18:20:06 EST 2012
On Sat, 2012-11-24 at 23:47 +0100, Turbo Fredriksson wrote:
> I'll create a 'var/cache/apt' which isn't compressed then. Thanx.
For references, I looked up the bug:
> * In Solaris/ZFS it's apparently possible to boot from a snapshot.
> Is this still possible in ZoL?
I haven't tested this.
> * Why must the pool first be exported and then imported? I'd rather
> not do this, since I have 13TB already mounted and in use...
> I assume it's done in the HOWTO(s) so that zfs.cache get's updated? But
> mine should already be, since it's been running (and rebooting) for about
> a year :)... ?
I'm not sure, but I'd tend to agree with your conclusion. In general, my
emphasis has been on the things that are *different* between my HOWTO
and Darik's (from which mine is forked). He likely knows more about that
> * Installing grub. My pool currently look like this:
> NAME STATE READ WRITE CKSUM
> share ONLINE 0 0 0
> raidz1-0 ONLINE 0 0 0
> scsi-SATA_ST31500341AS_9VS3S9YD ONLINE 0 0 0
> scsi-SATA_ST31500341AS_9VS08THF ONLINE 0 0 0
> scsi-SATA_ST31500341AS_9VS16S63 ONLINE 0 0 0
> raidz1-1 ONLINE 0 0 0
> scsi-SATA_ST31500341AS_9VS4XK4T ONLINE 0 0 0
> scsi-SATA_ST31500341AS_9VS4Q3F4 ONLINE 0 0 0
> scsi-SATA_ST1500DL003-9VT_5YD1F2KF ONLINE 0 0 0
> raidz1-2 ONLINE 0 0 0
> scsi-SATA_ST31500341AS_9VS3SAWS ONLINE 0 0 0
> scsi-SATA_ST31500341AS_9VS4R2MJ ONLINE 0 0 0
> scsi-SATA_ST31500341AS_9VS13W11 ONLINE 0 0 0
> raidz1-3 ONLINE 0 0 0
> scsi-SATA_ST31500341AS_9VS4VT5R ONLINE 0 0 0
> scsi-SATA_ST31500341AS_9VS4Q38C ONLINE 0 0 0
> scsi-SATA_ST31500341AS_9VS4WM30 ONLINE 0 0 0
> raidz1-4 ONLINE 0 0 0
> scsi-SATA_ST31500341AS_9VS4VT5X ONLINE 0 0 0
> scsi-SATA_ST31500341AS_9VS4WWPA ONLINE 0 0 0
> scsi-SATA_ST31500341AS_9VS0H3A9 ONLINE 0 0 0
> ata-Corsair_Force_3_SSD_11486508000008952122 ONLINE 0 0 0
> Where would I write grub?
I haven't done much testing with raidz roots.
My vision (which is not a reality at this time) would be for GRUB to
realize that it's a raidz and write the bootloader bits to ALL of the
disks, using the ZFS embedding area even if it's a wholedisk setup (to
avoid the need for a BIOS boot partition). And finally, zpool attach
operations (maybe through the to-be-written zevent daemon) should result
in GRUB installing the bootloader bits to the new drive. Installing to
all drives seems silly (but probably not harmful) when you have 15, but
with 2 or 3 it makes a lot more sense.
> Maybe on the cache dev, and have the BIOS boot from that
That could work. Just make sure you're okay with what that means if that
> Is there a least required version of grub to be able to do ZFS booting?
You need a patched GRUB, like that from the PPA. I've gotten some
patches accepted upstream, but there's at least one more that'll be
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