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From: John Robinson <john.robinson@anonymous.org.uk>
To: Greg Freemyer <greg.freemyer@norcrossgroup.com>
Cc: Bill Davidsen <davidsen@tmr.com>, Neil Brown <neilb@suse.de>,
	James Bottomley <James.Bottomley@hansenpartnership.com>,
	Ric Wheeler <rwheeler@redhat.com>,
	linux-raid <linux-raid@vger.kernel.org>,
	Dongjun Shin <djshin90@gmail.com>,
	IDE/ATA development list <linux-ide@vger.kernel.org>
Subject: Re: SSD data reliable vs. unreliable [Was: Re: Data Recovery from SSDs - Impact of trim?]
Date: Thu, 29 Jan 2009 01:49:55 +0000	[thread overview]
Message-ID: <49810B43.20108@anonymous.org.uk> (raw)
In-Reply-To: <7fce22690901281556h67fb353dp879f88e6c2a76eaf@mail.gmail.com>

On 28/01/2009 23:56, Greg Freemyer wrote:
> Once discard calls get into linux file systems mdraid and/or device
> mapper could implement linux's own thin provisioning implementation.
> Even with traditional disks that don't support unmap.  I gather that
> is what the EMCs of the world will be doing in their platforms.
> 
> http://en.wikipedia.org/wiki/Thin_provisioning

Sounds more like a device mapper or LVM thing (than md/RAID) to me, but 
I'd definitely agree that this would be another great reason for block 
devices to implement map/unmap.

And I wonder if there's room for another dm/md device type which just 
implements these usage maps over traditional devices which don't support 
unmap (much as I was wondering a few weeks back about a soft DIF 
implementation over e.g. SATA devices). Darn it, I might just have to 
dig out my school books on C; it's a while since I offered a kernel patch.

Cheers,

John.


  parent reply	other threads:[~2009-01-29  1:49 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2009-01-22 23:53 SSD data reliable vs. unreliable [Was: Re: Data Recovery from SSDs - Impact of trim?] Greg Freemyer
2009-01-23 20:40 ` Ric Wheeler
2009-01-23 22:24   ` James Bottomley
2009-01-23 23:26     ` Greg Freemyer
2009-01-23 23:35       ` Ric Wheeler
     [not found]         ` <7fce22690901260659u30ffd634m3fb7f75102141ee9@mail.gmail.com>
2009-01-26 16:22           ` Ric Wheeler
2009-01-26 17:34             ` Greg Freemyer
2009-01-26 17:46               ` Ric Wheeler
2009-01-26 17:47               ` James Bottomley
2009-01-27  5:16                 ` Neil Brown
2009-01-27 10:49                   ` John Robinson
2009-01-28 20:11                     ` Bill Davidsen
     [not found]                       ` <7fce22690901281556h67fb353dp879f88e6c2a76eaf@mail.gmail.com>
2009-01-29  1:49                         ` John Robinson [this message]
2009-01-27 11:23                   ` Ric Wheeler
2009-01-28 20:28                     ` Bill Davidsen
2009-01-27 14:48                   ` James Bottomley
2009-01-27 14:54                     ` Ric Wheeler
2009-01-26 17:51               ` Mark Lord
2009-01-26 18:09                 ` Greg Freemyer
2009-01-26 18:21                   ` Mark Lord
2009-01-29 14:07                     ` Dongjun Shin
2009-01-29 15:46                       ` Mark Lord
2009-01-29 16:27                         ` Greg Freemyer
2009-01-30 15:43                           ` Bill Davidsen

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