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From: Rich Freeman <rich0@gentoo.org>
To: gentoo-user@lists.gentoo.org
Subject: Re: [gentoo-user] Hard drive storage questions
Date: Tue, 28 Apr 2015 13:38:55 -0400	[thread overview]
Message-ID: <CAGfcS_nCKvCoquH=+T=_c3YDAnhBk2L9=6b9=GrikuWy2MC7Sw@mail.gmail.com> (raw)
In-Reply-To: <20150428162448.160e1683@digimed.co.uk>

On Tue, Apr 28, 2015 at 11:24 AM, Neil Bothwick <neil@digimed.co.uk> wrote:
> The same is also  possible with BTRFS, including built in RAID. RAID5 in
> btrfs is expermiental, but its RAID1 is like RAID5 in some ways, such as
> giving the capacity of n-1 disks and tolerating a single disk failure.
>

btrfs raid5 is still fairly experimental (though now it supports
recovery) and works more-or-less how you'd expect raid5 to work.
Raid1 on btrfs gives you the capacity of n/2 and not n-1 disks, as you
would expect.  It does allow disks to be of different size, in which
case it gives you up to n/2 capacity (and usually more than you'd get
with traditional raid1 - it tries to fill the largest disks first so
3+1+1+1 TB will give you 3TB of storage, not 2TB as you'd get with
mdadm raid1).

Here is a btrfs raid1:
df -h
Filesystem                   Size  Used Avail Use% Mounted on
/dev/sdh2                    3.2T  2.7T  477G  86% /data

btrfs fi df /data
Data, RAID1: total=2.93TiB, used=2.65TiB
System, RAID1: total=32.00MiB, used=472.00KiB
Metadata, RAID1: total=16.00GiB, used=14.08GiB
GlobalReserve, single: total=512.00MiB, used=0.00B

btrfs fi sho /data
Label: 'datafs'  uuid: cd074207-9bc3-402d-bee8-6a8c77d56959
        Total devices 5 FS bytes used 2.67TiB
        devid    1 size 2.73TiB used 2.63TiB path /dev/sdh2
        devid    2 size 931.32GiB used 832.03GiB path /dev/sda2
        devid    3 size 931.32GiB used 834.00GiB path /dev/sde2
        devid    4 size 931.32GiB used 832.00GiB path /dev/sdd2
        devid    5 size 931.32GiB used 833.00GiB path /dev/sdb2


2.7TiB of data is stored on the array, which has nearly exhausted the
space of 6.4TiB of drives (or 7TB).  There are ~500GiB free, which
would let me store ~250GiB of data.

-- 
Rich


  reply	other threads:[~2015-04-28 17:39 UTC|newest]

Thread overview: 59+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-04-28  8:39 [gentoo-user] Hard drive storage questions Dale
2015-04-28 14:49 ` Francisco Ares
2015-04-28 15:01 ` Alan McKinnon
2015-04-28 15:24   ` Neil Bothwick
2015-04-28 17:38     ` Rich Freeman [this message]
2015-04-28 18:11       ` Neil Bothwick
2015-04-28 18:31         ` Rich Freeman
2015-04-28 18:41           ` Neil Bothwick
2015-04-28 22:02     ` [gentoo-user] " walt
2015-04-29  1:24       ` Rich Freeman
2015-04-29  6:20       ` Alan McKinnon
2015-04-29 14:31         ` Grant Edwards
2015-04-29  6:13     ` [gentoo-user] " Alan McKinnon
2015-04-29  7:52       ` Neil Bothwick
2015-05-04  7:39         ` Dale
2015-05-04  7:46           ` Neil Bothwick
2015-05-04  8:13             ` Mick
2015-05-04  8:26               ` Dale
2015-05-04  8:23             ` Dale
2015-05-04 10:31               ` Neil Bothwick
2015-05-04 10:40                 ` Dale
2015-05-04 11:26                   ` Neil Bothwick
2015-05-09 10:56                     ` Dale
2015-05-09 12:59                       ` Rich Freeman
2015-05-09 14:46                         ` Todd Goodman
2015-05-09 18:16                           ` Rich Freeman
2015-05-04 11:35                 ` Rich Freeman
2015-05-04 18:42                   ` Nuno Magalhães
2015-05-05  6:41                     ` Alan McKinnon
2015-05-05 10:56                     ` Rich Freeman
2015-05-05 11:33                       ` Neil Bothwick
2015-05-05 12:05                         ` Mick
2015-05-05 12:21                           ` Neil Bothwick
2015-05-05 12:39                             ` Mick
2015-05-05 12:53                             ` Rich Freeman
2015-05-05 21:50                               ` Neil Bothwick
2015-05-05 22:21                                 ` Bill Kenworthy
2015-05-05 22:33                                   ` Bill Kenworthy
2015-05-04 10:57               ` Alan Mackenzie
2015-04-28 15:02 ` Rich Freeman
2015-05-04  7:23 ` Dale
2015-05-05  3:01   ` Walter Dnes
  -- strict thread matches above, loose matches on Subject: below --
2018-11-09  1:16 Dale
2018-11-09  1:31 ` Jack
2018-11-09  1:43   ` Dale
2018-11-09  2:04     ` Andrew Lowe
2018-11-09  2:07     ` Bill Kenworthy
2018-11-09  8:39       ` Neil Bothwick
2018-11-09  2:29 ` Rich Freeman
2018-11-09  8:17   ` Bill Kenworthy
2018-11-09 13:25     ` Rich Freeman
2018-11-09  9:02   ` J. Roeleveld
2018-11-11  0:45   ` Dale
2018-11-11 21:41     ` Wol's lists
2018-11-11 22:17       ` Dale
2018-11-09  9:24 ` Wols Lists
2015-04-27  7:41 Dale
2015-04-28 18:25 ` Daniel Frey
2015-04-28 21:23   ` Dale

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