From: Roberto Spadim <roberto@spadim.com.br>
To: doug@easyco.com
Cc: linux-raid@vger.kernel.org
Subject: Re: SSD - TRIM command
Date: Mon, 21 Feb 2011 16:57:05 -0300 [thread overview]
Message-ID: <AANLkTi=H-SowrrifRgzTGbF4VEk0WcXCRP0P6G-OtpRL@mail.gmail.com> (raw)
In-Reply-To: <AANLkTikCxjXbTAPNX-OQBMeNfUa4zKzaXk=C078Z837x@mail.gmail.com>
>Then again, my attitude
> about this is very arrogant and I think the trim spec was broken from
> the beginning.
maybe... we could put all harddisk firmware at linux code... why we
need reallocation of harddisks? we need when filesystem don´t do it
we question is: can we implement TRIM at MD device?
2011/2/21 Doug Dumitru <doug@easyco.com>:
> To be technically accurate, trim is a hint to a storage device that
> has a "block translation layer" that can take advantage of knowing
> that a block contains no meaningful data.
>
> Flash needs trim only if flash has an FTL (Flash Translation Layer)
> that is re-mapping blocks in such a manner as free blocks are helpful
> in making this process more efficient. Older SSDs did not support
> trim and had no real need for it. If you look at the FTL used with
> simple Flash (think CF cards, SD cards, and USB sticks) trim does not
> help them. Trim and wear leveling are un-related and don't really
> impact each other.
>
> On the linux side trim is "discard". This is actually a much better
> abstraction as it does not imply SSDs.
>
> Any type of block device that does dynamic block remapping will likely
> be helped (at least somewhat) by discard. The only examples of this I
> can think of off-hand are 1) my Flash SuperCharger code, and 2)
> block-level de-dupe engines. I am sure other examples will be created
> over time.
>
> Hopefully, discard can be driven down the stack. I would personally
> prefer the linux community declare that discard and zero writes are
> identical. If an SSD supports trim and linux wants to translate a
> discard into a trim at the device driver layer, and the SSD is
> non-deterministic, then that SSD is broken. Then again, my attitude
> about this is very arrogant and I think the trim spec was broken from
> the beginning.
>
> --
> Doug Dumitru
> EasyCo LLC
> --
> To unsubscribe from this list: send the line "unsubscribe linux-raid" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at http://vger.kernel.org/majordomo-info.html
>
--
Roberto Spadim
Spadim Technology / SPAEmpresarial
--
To unsubscribe from this list: send the line "unsubscribe linux-raid" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
next prev parent reply other threads:[~2011-02-21 19:57 UTC|newest]
Thread overview: 70+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-02-07 20:07 SSD - TRIM command Roberto Spadim
2011-02-08 17:37 ` maurice
2011-02-08 18:31 ` Roberto Spadim
[not found] ` <AANLkTik5SumqyTN5LZVntna8nunvPe7v38TSFf9eCfcU@mail.gmail.com>
2011-02-08 20:50 ` Roberto Spadim
2011-02-08 21:18 ` maurice
2011-02-08 21:33 ` Roberto Spadim
2011-02-09 7:44 ` Stan Hoeppner
2011-02-09 9:05 ` Eric D. Mudama
2011-02-09 15:45 ` Chris Worley
2011-02-09 13:29 ` David Brown
2011-02-09 14:39 ` Roberto Spadim
2011-02-09 15:00 ` Scott E. Armitage
2011-02-09 15:52 ` Chris Worley
2011-02-09 19:15 ` Doug Dumitru
2011-02-09 19:22 ` Roberto Spadim
2011-02-09 16:19 ` Eric D. Mudama
2011-02-09 16:28 ` Scott E. Armitage
2011-02-09 17:17 ` Eric D. Mudama
2011-02-09 18:18 ` Roberto Spadim
2011-02-09 18:24 ` Piergiorgio Sartor
2011-02-09 18:30 ` Roberto Spadim
2011-02-09 18:38 ` Piergiorgio Sartor
2011-02-09 18:46 ` Roberto Spadim
2011-02-09 18:52 ` Roberto Spadim
2011-02-09 19:13 ` Piergiorgio Sartor
2011-02-09 19:16 ` Roberto Spadim
2011-02-09 19:21 ` Piergiorgio Sartor
2011-02-09 19:27 ` Roberto Spadim
2011-02-21 18:24 ` Phillip Susi
2011-02-21 18:30 ` Roberto Spadim
2011-02-09 15:49 ` David Brown
2011-02-21 18:20 ` Phillip Susi
2011-02-21 18:25 ` Roberto Spadim
2011-02-21 18:34 ` Phillip Susi
2011-02-21 18:48 ` Roberto Spadim
2011-02-21 18:51 ` Mathias Burén
2011-02-21 19:32 ` Roberto Spadim
2011-02-21 19:38 ` Mathias Burén
2011-02-21 19:39 ` Mathias Burén
2011-02-21 19:43 ` Roberto Spadim
2011-02-21 20:45 ` Phillip Susi
2011-02-21 19:39 ` Roberto Spadim
2011-02-21 19:51 ` Doug Dumitru
2011-02-21 19:57 ` Roberto Spadim [this message]
2011-02-21 20:47 ` Phillip Susi
2011-02-21 21:02 ` Mathias Burén
2011-02-21 22:52 ` Roberto Spadim
2011-02-21 23:41 ` Mathias Burén
2011-02-21 23:42 ` Mathias Burén
2011-02-21 23:52 ` Roberto Spadim
2011-02-22 0:25 ` Mathias Burén
2011-02-22 0:30 ` Brendan Conoboy
2011-02-22 0:36 ` Eric D. Mudama
2011-02-22 1:46 ` Roberto Spadim
2011-02-22 1:52 ` Mathias Burén
2011-02-22 1:55 ` Roberto Spadim
2011-02-22 2:01 ` Eric D. Mudama
2011-02-22 2:02 ` Mikael Abrahamsson
2011-02-22 2:22 ` Guy Watkins
2011-02-22 2:27 ` Roberto Spadim
2011-02-22 3:45 ` NeilBrown
2011-02-22 4:37 ` Roberto Spadim
2011-02-22 2:38 ` Phillip Susi
2011-02-22 3:29 ` Roberto Spadim
2011-02-22 3:42 ` Roberto Spadim
2011-02-22 4:04 ` Phillip Susi
2011-02-22 4:30 ` Roberto Spadim
2011-02-22 14:45 ` Phillip Susi
2011-02-22 17:15 ` Roberto Spadim
2011-02-22 0:32 ` Eric D. Mudama
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to='AANLkTi=H-SowrrifRgzTGbF4VEk0WcXCRP0P6G-OtpRL@mail.gmail.com' \
--to=roberto@spadim.com.br \
--cc=doug@easyco.com \
--cc=linux-raid@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.