Re: ext4 bug ? "Intel 320 SSD write performance – contd."

From: Stephen Clark
Date: Tue Nov 01 2011 - 09:34:08 EST


On 10/31/2011 05:09 PM, Ted Ts'o wrote:
On Mon, Oct 31, 2011 at 09:38:37PM +0100, Vincent Pelletier wrote:
Reading this blog post[1], I thought the "2nd iteration" results could be
considered a bug in mkfs.ext4 (and possibly any mkfs implementation):
shouldn't mkfs run [FI]TRIM on its target before creating filesystem
structure ?
It's not enabled by default, because there are crappy SSD's out there
where use of the TRIM command will turn them into bricks. (No, it's
not the Intel X-25 drives that I'm worried about.)

So I (and the distributions) don't want to make it the default, since
if you buy crap drives and then mke2fs turns them into bricks, who are
you likely to blame? The crap SSD manufacturer? Yourself for trying
to buy SSD's on the cheap? Or the program that issued the TRIM
command?

You can enable the trim behaviour by default by adding to your
/etc/mke2fs.conf file:

[defaults]
discard = true

But then it's on your head if anything bad happens. :-/

- Ted

<snip>

What about using discard in fstab like:
LABEL=/ / ext4 defaults,discard,noatime,nodiratime 1 1

Thanks,
Steve

--

"They that give up essential liberty to obtain temporary safety,
deserve neither liberty nor safety." (Ben Franklin)

"The course of history shows that as a government grows, liberty
decreases." (Thomas Jefferson)



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