From: Mike Snitzer <snitzer@redhat.com>
To: Phillip Susi <psusi@cfl.rr.com>
Cc: Ron Johnson <ron.l.johnson@cox.net>,
LVM general discussion and development <linux-lvm@redhat.com>
Subject: Re: [linux-lvm] Advanced Format disks mixed with regular disks?
Date: Wed, 16 Mar 2011 18:55:39 -0400 [thread overview]
Message-ID: <20110316225539.GA3662@redhat.com> (raw)
In-Reply-To: <4D812183.6000901@cfl.rr.com>
On Wed, Mar 16 2011 at 4:45pm -0400,
Phillip Susi <psusi@cfl.rr.com> wrote:
> On 3/14/2011 1:17 PM, Mike Snitzer wrote:
> > Both LVM2 and Device Mapper have been updated to accommodate stacking
> > such a mix of drives.
> >
> > See this for a bit more detail:
> > http://people.redhat.com/msnitzer/docs/io-limits.txt
> >
> > Particularly, the "Stacking I/O Limits" section.
> >
> > The concern raised for partial (4k) writes to the 512b drive was
> > discussed a bit more here: http://lkml.org/lkml/2010/2/22/295
>
> Unfortunately this does not help with the WD EARS model drives ( are
> there any other 4kb sector drives on the market now? ), since they lie
> and report that they have 512 byte sectors.
I'm not following what you're saying. The kernel's blk_stack_limits()
infrastructure accounts for "desktop" class 4K devices too (4K physical,
512b logical) -- as does DM and lvm2.
If given:
"desktop" class drive:
physical_block_size=4096
logical_block_size=512
minimum_io_size=4096
optimal_io_size=0
conventional 512 drive:
physical_block_size=512
logical_block_size=512
minimum_io_size=512
optimal_io_size=0
Stacking these drives would result in a logical device that has:
physical_block_size=4096
logical_block_size=512
minimum_io_size=4096
optimal_io_size=0
And yes, there are native 4K "enterprise" class drives (4K physical, 4K
logical) in the market.
Mike
next prev parent reply other threads:[~2011-03-16 22:55 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-03-14 16:47 [linux-lvm] Advanced Format disks mixed with regular disks? Ron Johnson
2011-03-14 17:17 ` Mike Snitzer
2011-03-14 17:32 ` Les Mikesell
2011-03-14 18:02 ` Mike Snitzer
2011-03-14 18:09 ` Ron Johnson
2011-03-14 19:13 ` Ron Johnson
2011-03-14 20:00 ` Mike Snitzer
2011-03-15 8:02 ` Karel Zak
2011-03-15 14:24 ` Stuart D. Gathman
2011-03-15 17:36 ` Stuart D. Gathman
2011-03-15 0:15 ` John Drescher
2011-03-16 20:45 ` Phillip Susi
2011-03-16 22:55 ` Mike Snitzer [this message]
2011-03-16 23:11 ` Les Mikesell
2011-03-17 0:02 ` Mike Snitzer
2011-03-17 0:18 ` Mike Snitzer
2011-03-17 0:12 ` Phillip Susi
2011-03-17 0:39 ` Martin K. Petersen
2011-03-17 14:21 ` hansbkk
2011-03-17 23:47 ` Ron Johnson
2011-03-22 10:23 ` Karel Zak
2011-03-22 16:51 ` Les Mikesell
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