From: Roberto Spadim <roberto@spadim.com.br>
To: "Mathias Burén" <mathias.buren@gmail.com>
Cc: "Eric D. Mudama" <edmudama@bounceswoosh.org>,
Phillip Susi <psusi@cfl.rr.com>,
David Brown <david@westcontrol.com>,
linux-raid@vger.kernel.org
Subject: Re: SSD - TRIM command
Date: Mon, 21 Feb 2011 22:55:24 -0300 [thread overview]
Message-ID: <AANLkTim_F1wqvLprPvytVAMLnbDcr71ys-38WcsFpFkB@mail.gmail.com> (raw)
In-Reply-To: <AANLkTi=-hJ5SeTsUNT=in0GBNUQB=4uvdumrvuakZXgq@mail.gmail.com>
it can be used for badblock reallocation if harddisk have it
a harddisk is near to NOR ssd with variable accesstime, if head is
near sector to be read/write accesstime is small, if sector is far
from head, access time increase (normaly <=1 disk revolution if head
control system is good, for 7200rpm 1revolution is near to 8.33ms)
2011/2/21 Mathias Burén <mathias.buren@gmail.com>:
> On 22 February 2011 01:46, Roberto Spadim <roberto@spadim.com.br> wrote:
>> if it make sense on ssd, harddisk make sense too, it's a block device
>> like ssd, the diference of ssd/harddisk? access time,
>> bytes(bits)/block, life time
>> bad block exist in ssd and harddisk, ssd can realloc online, some harddisks too
>>
>>> no, because the host may immediately write to a trim'd sector
>> yes, filesystem know where exists a unused sector
>> if device (harddisk/ssd) know and have a reallocation algorithm, it
>> can realloc without telling filesystem to do it (that's why TRIM is
>> interesting)
>> since today ssd use NAND (not NOR) the block size isn't 1 bit like a
>> harddisk head. trim for harddisk only make sense for badblock
>> reallocation
>> --------------------------
>> getting back to the first question, can MD support trim? yes/no/not
>> now/some levels and layouts only?
>> --
>> Roberto Spadim
>> Spadim Technology / SPAEmpresarial
>
> This explains a bit why trim is good for SSDs and has nothing to do
> with harddrives at all, since they use spinning platters and not
> chips. http://www.anandtech.com/show/2738/10
>
> // Mathias
> --
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>
--
Roberto Spadim
Spadim Technology / SPAEmpresarial
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next prev parent reply other threads:[~2011-02-22 1:55 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
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 [this message]
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
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