From: Calvin Walton <calvin.walton@kepstin.ca>
To: Marc MERLIN <marc@merlins.org>
Cc: Milan Broz <mbroz@redhat.com>,
Chris Mason <chris.mason@oracle.com>,
linux-btrfs@vger.kernel.org, jeff@deserettechnology.com
Subject: Re: brtfs on top of dmcrypt with SSD. No corruption iff write cache off?
Date: Wed, 15 Feb 2012 10:42:43 -0500 [thread overview]
Message-ID: <1329320563.1897.6.camel@ayu> (raw)
In-Reply-To: <20120213001400.GD31989@merlins.org>
On Sun, 2012-02-12 at 16:14 -0800, Marc MERLIN wrote:
> Considering that I have a fairly new crucial 256GB SDD, I'm going to assume
> that this bit applies to me:
> "On the other side, TRIM is usually overrated. Drive itself should keep good
> performance even without TRIM, either by using internal garbage collecting
> process or by some area reserved for optimal writes handling."
>
> So it sounds like I should just not give the "ssd" mount option to btrfs,
> and not worry about TRIM.
The 'ssd' option on btrfs is actually completely unrelated to trim
support. Instead, it changes how blocks are allocated on the device,
taking advantage of the the improved random read/write speed. The 'ssd'
option should be autodetected on most SSDs, but I don't know if this is
handled correctly when you're using dm-crypt. (Btrfs prints a message at
mount time when it autodetects this.) It shouldn't hurt to leave it.
Discard is handled with a separate mount option on btrfs (called
'discard'), and is disabled by default even if you have the 'ssd' option
enabled, because of the negative performance impact it has had on some
SSDs.
--
Calvin Walton <calvin.walton@kepstin.ca>
next prev parent reply other threads:[~2012-02-15 15:42 UTC|newest]
Thread overview: 68+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-01-30 0:37 brtfs on top of dmcrypt with SSD. No corruption iff write cache off? Marc MERLIN
2012-02-01 17:56 ` Chris Mason
2012-02-02 3:23 ` Marc MERLIN
2012-02-02 12:42 ` Chris Mason
[not found] ` <20120202152722.GI12429@merlins.org>
2012-02-12 22:32 ` Marc MERLIN
2012-02-12 23:47 ` Milan Broz
2012-02-13 0:14 ` Marc MERLIN
2012-02-15 15:42 ` Calvin Walton [this message]
2012-02-15 16:55 ` Marc MERLIN
2012-02-15 16:59 ` Hugo Mills
2012-02-22 10:28 ` Justin Ossevoort
2012-02-22 11:07 ` Hugo Mills
2012-02-16 6:33 ` Chris Samuel
2012-02-18 12:33 ` Martin Steigerwald
2012-02-18 12:39 ` Martin Steigerwald
2012-02-18 12:49 ` Martin Steigerwald
2012-07-18 18:13 ` brtfs on top of dmcrypt with SSD -> Trim or no Trim Marc MERLIN
2012-07-18 20:04 ` Fajar A. Nugraha
2012-07-18 20:37 ` Marc MERLIN
2012-07-18 21:34 ` Clemens Eisserer
2012-07-18 21:48 ` Marc MERLIN
2012-07-18 21:49 ` Martin Steigerwald
2012-07-18 22:04 ` Marc MERLIN
2012-07-19 10:40 ` Martin Steigerwald
2012-07-22 18:58 ` brtfs on top of dmcrypt with SSD -> ssd or nossd + crypt performance? Marc MERLIN
2012-07-22 19:35 ` Martin Steigerwald
2012-07-22 19:43 ` Martin Steigerwald
2012-07-22 20:44 ` Marc MERLIN
2012-07-22 22:41 ` brtfs on top of dmcrypt with SSD -> file access 5x slower than spinning disk Marc MERLIN
2012-07-23 6:42 ` How can btrfs take 23sec to stat 23K files from an SSD? Marc MERLIN
2012-07-24 7:56 ` Martin Steigerwald
2012-07-27 4:40 ` Marc MERLIN
2012-07-27 11:08 ` Chris Mason
2012-07-27 18:42 ` Marc MERLIN
2012-02-18 16:07 ` brtfs on top of dmcrypt with SSD. No corruption iff write cache off? Marc MERLIN
2012-02-19 0:53 ` Clemens Eisserer
2012-07-25 15:45 du -s src is a lot slower on SSD than spinning disk in the same laptop Marc MERLIN
[not found] ` <alpine.LFD.2.00.1207252023080.4340@(none)>
2012-07-25 23:38 ` Marc MERLIN
2012-07-26 3:32 ` Ted Ts'o
2012-07-26 3:35 ` Marc MERLIN
2012-07-26 6:54 ` Marc MERLIN
2012-08-01 5:30 ` Marc MERLIN
2012-08-01 6:01 ` How can btrfs take 23sec to stat 23K files from an SSD? Marc MERLIN
2012-08-01 6:08 ` Fajar A. Nugraha
2012-08-01 6:21 ` Marc MERLIN
2012-08-01 21:57 ` Martin Steigerwald
2012-08-02 5:07 ` Marc MERLIN
2012-08-02 11:18 ` Martin Steigerwald
2012-08-02 17:39 ` Marc MERLIN
2012-08-02 20:20 ` Martin Steigerwald
2012-08-02 20:44 ` Marc MERLIN
2012-08-02 21:21 ` Martin Steigerwald
2012-08-02 21:49 ` Marc MERLIN
2012-08-03 18:45 ` Martin Steigerwald
2012-08-16 7:45 ` Marc MERLIN
2012-08-02 11:25 ` Martin Steigerwald
2012-08-01 6:36 ` Chris Samuel
2012-08-01 6:40 ` Marc MERLIN
2012-08-01 8:18 ` du -s src is a lot slower on SSD than spinning disk in the same laptop Spelic
2012-08-16 7:50 ` Marc MERLIN
[not found] ` <502CC2A2.4010506@shiftmail.org>
2012-08-16 17:55 ` Marc MERLIN
2012-09-05 16:52 ` ext4 crash with 3.5.2 in ext4_ext_remove_space Marc MERLIN
2012-09-05 17:50 ` Lukáš Czerner
2012-09-05 17:53 ` Marc MERLIN
2012-09-06 4:24 ` Marc MERLIN
2012-09-07 15:19 ` Marc MERLIN
2012-09-07 15:39 ` Lukáš Czerner
2012-09-07 15:51 ` Marc MERLIN
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