From: Calvin Walton <calvin.walton@kepstin.ca>
To: Tomasz Chmielewski <tch@virtall.com>
Cc: "linux-btrfs@vger.kernel.org" <linux-btrfs@vger.kernel.org>
Subject: Re: RAID-1 - suboptimal write performance?
Date: Fri, 16 May 2014 14:06:24 -0400 [thread overview]
Message-ID: <1400263584.979.17.camel@sasami.ottawa.blindsidenetworks.com> (raw)
In-Reply-To: <20140516164815.1c33149b@s9>
On Fri, 2014-05-16 at 16:48 +0100, Tomasz Chmielewski wrote:
> While doing rsyncs of large archives from one RAID-1 btrfs filesystem
> to another RAID-1 btrfs filesystem:
>
> btrfs filesystem 1: sda + sdb (RAID-1), being copied to:
> btrfs filesystem 2: sdc + sdd (RAID-1)
> Server has 32 GB RAM
>
>
> I can observe the following:
>
>
> From time to time, rsync "freezes", while there is high IO on only *one*
> of write drives.
No comment on the performance issue, other than to say that I've seen
similar on RAID-10 before, I think.
> Also, what happens when the system crashes, and one drive has several
> hundred megabytes data more than the other one?
This shouldn't be an issue as long as you occasionally run a scrub or
balance. The scrub should find it and fix the missing data, and a
balance would just rewrite it as proper RAID-1 as a matter of course.
--
Calvin Walton <calvin.walton@kepstin.ca>
next prev parent reply other threads:[~2014-05-16 18:06 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-05-16 15:48 RAID-1 - suboptimal write performance? Tomasz Chmielewski
2014-05-16 18:06 ` Calvin Walton [this message]
2014-05-16 20:41 ` Tomasz Chmielewski
2014-05-16 21:36 ` Austin S Hemmelgarn
2014-05-18 18:49 ` Brendan Hide
2014-05-23 12:57 ` Roman Mamedov
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