[zfs-discuss] Very newbie question

Prakash Surya surya1 at llnl.gov
Wed Oct 23 13:09:37 EDT 2013


On Tue, Oct 22, 2013 at 06:52:18PM -0500, Richard Laager wrote:
> From your questions, it seems like my fork of the official HOWTO might
> be what you're looking for:
> https://github.com/rlaager/zfs/wiki/HOWTO-Install-Ubuntu-to-a-Native-ZFS-Root-Filesystem

I used a combination of this, Darik's HOWTO, and my own experience with
ZFS to set up my work desktop running ZFS root and ZFS /boot using a
mirror pair of disks.

I'm also running ZFS on root but using EXT for the /boot partition on my
home server.

Both configurations have worked out quite well for me so far.

-- 
Cheers, Prakash

> 
> In that HOWTO, I use the approach of creating wholedisk pools and then
> going back and putting a GRUB "BIOS Boot Partition" in the free space at
> the beginning of the disk (which exists to align the first partition to
> 1 MiB). Longer-term, I'd really like to write a patch for GRUB that
> would use the ZFS embedding area on the first partition when it's a
> wholedisk ZFS setup. (GRUB has support for using the embedding area when
> you're installing GRUB to a partition, but that's not what we're doing
> here and I've never tested it.)
> 
> That said, it *is* potentially quite fragile. Any update could break
> this. In particular, if building the ZFS modules fails, DKMS doesn't
> keep the old ones, I think. (Not that building should be failing, but I
> think you see my point about fragility.)
> 
> Darik (who does the Ubuntu PPA of the ZoL packages and maintains the
> upstream HOWTO) has seen issues where installations work fine for a
> while but then GRUB chokes on them at some point in the future. We had a
> post to this mailing list not too long ago with a problem like that. I
> haven't had the time to look into any of the specifics, so I can't give
> you a useful second opinion. Darik also warns in the upstream HOWTO
> specifically about ashift=12 being more fragile.
> 
> FWIW, I still use raid1 + MD + LVM for root and swap on my personal
> server, where I do use ZoL for data. On the other hand, LVM blew up on
> me and a colleague the other day. They are different hardware and we
> setup our servers completely independently. And for that matter, we set
> them up more-or-less the same as servers at work which did not have the
> same problem booting. So if LVM is going to be fragile too, maybe I
> should just do a ZFS root.
> 
> In the end, you'll have to decide on your own comfort level with the
> various trade-offs, and make sure you keep a boot CD/USB handy. And of
> course, make backups!
> 
> -- 
> Richard


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