From: Jim Salter <jim@jrs-s.net>
To: Chris Murphy <lists@colorremedies.com>,
Btrfs BTRFS <linux-btrfs@vger.kernel.org>
Subject: Re: btrfs-transaction blocked for more than 120 seconds
Date: Sun, 05 Jan 2014 12:54:44 -0500 [thread overview]
Message-ID: <52C99C64.2010209@jrs-s.net> (raw)
In-Reply-To: <8EE40903-FE21-4516-B2D8-4EB8DCE79376@colorremedies.com>
On 01/05/2014 12:09 PM, Chris Murphy wrote:
> I haven't read anything so far indicating defrag applies to the VM
> container use case, rather nodatacow via xattr +C is the way to go. At
> least for now.
Can you elaborate on the rationale behind database or VM binaries being
set nodatacow? I experimented with this*, and found no significant (to
me, anyway) performance enhancement with nodatacow on - maybe 10% at
best, and if I understand correctly, that implies losing the live
per-block checksumming of the data that's set nodatacow, meaning you
won't get automatic correction if you're on a redundant array.
All I've heard so far is "better performance" without any more detailed
explanation, and if the only benefit is an added MAYBE 10%ish
performance... I'd rather take the hit, personally.
* "experimented with this" == set up a Win2008R2 test VM and ran
HDTunePro for several runs on binaries stored with and without nodatacow
set, 5G of random and sequential read and write access per run.
next prev parent reply other threads:[~2014-01-05 17:54 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-12-31 11:46 btrfs-transaction blocked for more than 120 seconds Sulla
2014-01-01 12:37 ` Duncan
2014-01-01 20:08 ` Sulla
2014-01-02 8:38 ` Duncan
2014-01-03 1:24 ` Kai Krakow
2014-01-03 9:18 ` Duncan
2014-01-05 0:12 ` Sulla
2014-01-03 17:25 ` Marc MERLIN
2014-01-03 21:34 ` Duncan
2014-01-05 6:39 ` Marc MERLIN
2014-01-05 17:09 ` Chris Murphy
2014-01-05 17:54 ` Jim Salter [this message]
2014-01-05 19:57 ` Duncan
2014-01-05 20:44 ` Chris Murphy
2014-01-08 3:22 ` Marc MERLIN
2014-01-08 9:45 ` Duncan
2014-01-04 20:48 ` Roger Binns
2014-01-02 8:49 ` Jojo
2014-01-05 20:32 ` Chris Murphy
2014-01-05 21:17 ` Sulla
2014-01-05 22:36 ` Brendan Hide
2014-01-05 22:57 ` Roman Mamedov
2014-01-07 10:22 ` Brendan Hide
2014-01-06 0:15 ` Chris Murphy
2014-01-06 0:19 ` Chris Murphy
2014-01-05 23:48 ` Chris Murphy
2014-01-05 23:57 ` Chris Murphy
2014-01-06 0:25 ` Sulla
2014-01-06 0:49 ` Chris Murphy
[not found] ` <52CA06FE.2030802@gmx.at>
2014-01-06 1:55 ` Chris Murphy
[not found] <ADin1n00P0VAdqd01DioM9>
2014-01-05 20:44 ` Duncan
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