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 14:31:23 -0400 [thread overview]
Message-ID: <CAGfcS_=Yrkmc=+oDAY+vJaUUExL94QO7JfoDreKN3C1oJfFL7A@mail.gmail.com> (raw)
In-Reply-To: <20150428191112.6f1914c4@digimed.co.uk>
On Tue, Apr 28, 2015 at 2:11 PM, Neil Bothwick <neil@digimed.co.uk> wrote:
> On Tue, 28 Apr 2015 13:38:55 -0400, Rich Freeman 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,
>
> You're right, I was clearly confused (an oxymoron?) when I wrote that.
>
> So RAID1 gives less capacity than RAID5 on BTRFS, but it is stable (in
> btrfs terms).
>
Correct.
For drives of identical size and not using compression, I'd expect
space use on btrfs to be equivalent to the same raid level on
mdadm+lvm+ext4. With mixed drives you will potentially get more space
on btrfs, and compression will of course get you more space.
As far as data security goes there is a tradeoff. Btrfs is still
immature and I seem to have issues with it 1-2 times per year (but
I've yet to have unrecoverable data loss). On the other hand, btrfs
does do full data checksumming which means you're less likely to lose
data due to issues with the physical storage than with mdadm - as with
zfs it always checks the checksum and will recover from another disk
if possible, and in the event of raid disparity it always knows which
(if any) of the copies is right.
I'm hopeful that at some point I'll be able to recommend it without
reservation. Right now, that isn't entirely the case. I'm still
patching the 3.18 kernel series so that it actually mounts my root
partition when whatever is causing it to panic (probably also btrfs)
does so (the patch is in the queue, but hasn't made it to 3.18 yet for
some reason - I believe it has been in the other stable series for a
release or two now).
--
Rich
next prev parent reply other threads:[~2015-04-28 18:31 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
2015-04-28 18:11 ` Neil Bothwick
2015-04-28 18:31 ` Rich Freeman [this message]
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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