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From: Joe Thornber <thornber@redhat.com>
To: lilofile <lilofile@aliyun.com>,
	device-mapper development <dm-devel@redhat.com>
Cc: Ondrej Kozina <okozina@redhat.com>,
	Mike Snitzer <msnitzer@redhat.com>,
	"Alasdair G. Kergon" <agk@redhat.com>
Subject: Re: reply：  Thinly-Provisioned Logical Volumes
Date: Wed, 24 Sep 2014 09:37:47 +0100	[thread overview]
Message-ID: <20140924083747.GA8959@debian> (raw)
In-Reply-To: <ae586129-fc3a-41fe-8f2e-f3124c5ff58d@aliyun.com>

On Wed, Sep 24, 2014 at 10:11:00AM +0800, lilofile wrote:
> When I test thinly-provisioned logical volumes,I use dd if=/dev/zero of=/dev/mapper/mythinvolume count=1 bs=4k
> I only write 4k data in mythinvolume.but In thin_map functions, I found there are really  4K data written,but I found more read IO,probably dozens of read io. who issue these IO? 

Assuming the IO is going to the data device, and not the metadata
device, then the likely candidates would be read-ahead or udev.

- Joe

      parent reply	other threads:[~2014-09-24  8:37 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-09-20 14:19 Thinly-Provisioned Logical Volumes lilofile
2014-09-22  7:02 ` Zdenek Kabelac
2014-09-22 12:38 ` Mike Snitzer
2014-09-23 13:51 ` reply： " lilofile
2014-09-23 14:07   ` Zdenek Kabelac
2014-09-24  2:11   ` lilofile
2014-09-24  7:02     ` Zdenek Kabelac
2014-09-24  8:37     ` Joe Thornber [this message]

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