From: "Karl O. Pinc" <kop@meme.com>
To: dm-crypt@saout.de
Subject: Re: [dm-crypt] (More) Questions about LUKS / LVM
Date: Tue, 20 Sep 2011 13:06:47 -0500 [thread overview]
Message-ID: <1316542007.4663.0@mofo> (raw)
In-Reply-To: <20110920174129.GA25723@tansi.org> (from arno@wagner.name on Tue Sep 20 12:41:29 2011)
On 09/20/2011 12:41:29 PM, Arno Wagner wrote:
> On Tue, Sep 20, 2011 at 05:21:54PM +0200, Alexander Koch wrote:
> > Am 20.09.2011 13:47, schrieb Arno Wagner:
> > > With an SSD, things are a bit different. Due to the large
> > > internal sector size, the header can be in a sector that
> > > also has data that gets rewritten in it. As sectors are
> > > always written completely, the header then is at risk whenever
> > > that data gets rewritten.
> No connection with TRIM support. It is just that if the real
> block size is larger than the block size you are using,
> the SSD will rewrite/reloacte other data on writes smaller
> that the real sector size.
>
> What would need ot be done is to
> 1. Align LUKS header (partition start) to a real sector
> boundary.
> 2. Align the start of the filesystem area in that
> partition to a real sector boundary.
>
> Both are only possible to do realiably when you know the
> sector size. All of my 3 SSDs claim 512 byte sectors,
> which is almost certainly a lie.
Performance is also going to suck if you don't get
alignment right on drives with 4Kb sectors.
FWIW here are the links I use to deal with 4Kb sector issues.
http://ata.wiki.kernel.org/index.php/ATA_4_KiB_sector_issues
http://lists.debian.org/debian-user/2011/01/msg02021.html
Karl <kop@meme.com>
Free Software: "You don't pay back, you pay forward."
-- Robert A. Heinlein
next prev parent reply other threads:[~2011-09-20 18:06 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-09-20 10:36 [dm-crypt] (More) Questions about LUKS / LVM Robbie Smith
2011-09-20 10:52 ` Quentin Lefebvre
2011-09-20 11:47 ` Arno Wagner
2011-09-20 13:13 ` Milan Broz
2011-09-20 14:14 ` Arno Wagner
2011-09-20 14:52 ` Milan Broz
2011-10-03 6:17 ` Luca Berra
2011-10-03 10:55 ` Arno Wagner
2011-09-20 15:21 ` Alexander Koch
2011-09-20 16:12 ` Milan Broz
2011-09-20 17:41 ` Arno Wagner
2011-09-20 18:06 ` Karl O. Pinc [this message]
2011-09-20 18:19 ` Milan Broz
2011-09-21 10:22 ` Arno Wagner
2011-09-21 16:14 ` Dragan Milivojevic
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