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Re: btrfs: mixing raid0 and raid1 - How?

From David Christensen <dpchrist@holgerdanske.com>
Newsgroups linux.debian.user
Subject Re: btrfs: mixing raid0 and raid1 - How?
Date 2016-04-16 20:10 +0200
Message-ID <roCPn-7M4-5@gated-at.bofh.it> (permalink)
References <roswF-891-1@gated-at.bofh.it>
Organization linux.* mail to news gateway

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On 04/16/2016 12:00 AM, Matthias Bodenbinder wrote:
> I have 3 hard drive with 750 GB, 500 GB and 250 GB. I want to use btrfs as filesystem. This will be my first test installation of btrfs.
>
> My target is to get redundancy as well as a 750 GB data capacity. So I was thinking to create a raid0 with the 500 and 250 GB drive. This would result in a raid0 with 750 GB capacity. I want to add this raid0 as a mirror in a raid1 with the other 750 GB drive.
>
> But how do I do that?

250 GB HDD + 500 GB HDD can yield:
- 250 GB RAID0,
- 250 GB RAID1, or
- 750 GB JBOD.

To get 750 GB RAID0 or 750 GB RAID1, you need two 750 GB devices.


As other posters have mentioned, btrfs is fairly new on Linux and 
Debian.  I run Oldstable (Wheezy), and btrfs seems to mostly work as a 
file system (OOTB, btrfs root works, but GRUB can't read btrfs /boot). 
You may have to run a newer Debian and/or a newer kernel to get a btrfs 
with volume management and/or better Debian integration.


LVM has been stable on Debian for many years.  I used it in the past to 
create a 250 GB HDD + 250 GB HDD + 300 GB HDD => 800 GB JBOD, so LVM can 
certainly create a 250 GB HDD + 500 GB HDD => 750 GB JBOD.  I assume LVM 
can also create a 750 GB HDD + 750 GB JBOD => 750 GB RAID1.  The 
challenge would be setting everything up so that the 750 GB RAID1 comes 
up automagically at boot and tears down cleanly at shutdown.


mdadm is another stable technology that could work in your case.


David

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Thread

btrfs: mixing raid0 and raid1 - How? Matthias Bodenbinder <matthias@bodenbinder.de> - 2016-04-16 09:10 +0200
  Re: btrfs: mixing raid0 and raid1 - How? Luis Felipe Tabera Alonso <taberalf@unican.es> - 2016-04-16 10:50 +0200
    Re: btrfs: mixing raid0 and raid1 - How? Matthias Bodenbinder <matthias@bodenbinder.de> - 2016-04-16 12:10 +0200
      Re: btrfs: mixing raid0 and raid1 - How? Matthias Bodenbinder <matthias@bodenbinder.de> - 2016-04-16 12:20 +0200
      Re: btrfs: mixing raid0 and raid1 - How? Luis Felipe Tabera Alonso <taberalf@unican.es> - 2016-04-16 14:00 +0200
        Re: btrfs: mixing raid0 and raid1 - How? Andy Smith <andy@strugglers.net> - 2016-04-16 20:00 +0200
          Re: btrfs: mixing raid0 and raid1 - How? Matthias Bodenbinder <matthias@bodenbinder.de> - 2016-04-16 20:20 +0200
            Re: btrfs: mixing raid0 and raid1 - How? Andy Smith <andy@strugglers.net> - 2016-04-16 20:40 +0200
        Re: btrfs: mixing raid0 and raid1 - How? Matthias Bodenbinder <matthias@bodenbinder.de> - 2016-04-16 20:10 +0200
  Re: btrfs: mixing raid0 and raid1 - How? David Christensen <dpchrist@holgerdanske.com> - 2016-04-16 20:10 +0200

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