Re: raid1 on uneven-sized disks

[Hugo Mills <hugo@carfax.org.uk>]

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On Sun, Aug 09, 2015 at 02:29:53PM +0200, Jim MacBaine wrote:
> Hi,
> 
> How does btrfs handle raid1 on a bunch of uneven sized disks? Can I
> just keep adding arbitrarily sized disks to an existing raid1 and
> expect the file system to continue to keep two copies of everything,
> so I could survive the loss of any single disk without data loss? Does
> btrfs work this way?

   Yes, exactly.

   You may find that http://carfax.org.uk/btrfs-usage/ is helpful.

   Hugo.

> For backing up several machines at home, I use an old Debian machine
> which is equipped with some spare disks I could get my hands on.
> Currently that would be 2 x 2TB, 1 x 1.5TB , 3 x 1TB disks.
> 
> Traditionally I'm using rsync to create hardlinked backups on ext3/4
> on md-raid1. This setup has been working reliably for many years now,
> including the survival of two disk failures. But it is quite
> cumbersome to reshape the structure of the raids when I get a new
> disk, an old one fails, or space requirements change. A single btrfs
> with snapshots would be much easier to handle. I'm not aiming for
> absolute reliability here -- all the really important stuff is backed
> up in a third place as well. But I would rather not like my file
> system to be the weakest link in the backup chain.
> 
> Regards,
> Jim

-- 
Hugo Mills             | Guards! Help! We're being rescued!
hugo@... carfax.org.uk |
http://carfax.org.uk/  |
PGP: E2AB1DE4          |                       The Stainless Steel Rat Forever

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