From: Jonathan Tripathy <jonnyt@abpni.co.uk>
To: LVM general discussion and development <linux-lvm@redhat.com>
Subject: Re: [linux-lvm] Snapshots and disk re-use
Date: Thu, 24 Feb 2011 15:20:35 +0000 [thread overview]
Message-ID: <4D667743.3010102@abpni.co.uk> (raw)
In-Reply-To: <Pine.LNX.4.64.1102241011430.20629@bmsred.bmsi.com>
On 24/02/11 15:13, Stuart D. Gathman wrote:
> On Thu, 24 Feb 2011, Jonathan Tripathy wrote:
>
>>> Yes. To be more pedantic, the COW has copies of the original contents
>>> of blocks written to the origin since the snapshot. That is why you
>>> need to clear it to achieve your stated purpose. The origin blocks
>>> are written normally to the *-real volume (you can see these in
>>> the /dev/mapper directory).
>> But didn't you say that there is only one copy of the files stored physically
>> on disk?
> Yes. When you make the snapshot, there is only one copy, and the COW table
> is empty. AS YOU WRITE to the origin, each chunk written is saved to
> *-cow first before being written to *-real.
Got ya. So data that is being written to the origin, while the snapshot
exists, is the data that may leak, as it's saved to the COW first, then
copied over to real.
Hopefully an expert will let me know weather its safe to zero the COW
after I�ve finished with the snapshot.
next prev parent reply other threads:[~2011-02-24 15:21 UTC|newest]
Thread overview: 68+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-02-23 12:36 [linux-lvm] Snapshots and disk re-use Jonathan Tripathy
2011-02-23 13:09 ` Joe Thornber
2011-02-23 13:57 ` Jonathan Tripathy
2011-02-23 14:16 ` Joe Thornber
2011-02-23 14:18 ` Jonathan Tripathy
2011-02-23 16:12 ` Ray Morris
2011-02-23 16:55 ` Jonathan Tripathy
2011-02-23 17:54 ` Stuart D. Gathman
2011-02-23 18:05 ` Jonathan Tripathy
2011-02-23 19:34 ` Stuart D. Gathman
2011-02-23 18:05 ` Stuart D. Gathman
2011-02-23 18:19 ` Jonathan Tripathy
2011-02-23 18:39 ` Les Mikesell
2011-02-23 19:39 ` Stuart D. Gathman
2011-02-23 20:03 ` Les Mikesell
2011-02-23 20:37 ` Stuart D. Gathman
2011-02-23 20:49 ` Jonathan Tripathy
2011-02-23 23:25 ` Stuart D. Gathman
2011-02-23 23:42 ` Stuart D. Gathman
2011-02-24 0:09 ` Jonathan Tripathy
2011-02-24 0:32 ` Stuart D. Gathman
2011-02-24 0:37 ` Jonathan Tripathy
2011-02-24 0:40 ` Jonathan Tripathy
2011-02-24 2:00 ` Stuart D. Gathman
2011-02-24 7:33 ` Jonathan Tripathy
2011-02-24 14:50 ` Stuart D. Gathman
2011-02-24 14:57 ` Jonathan Tripathy
2011-02-24 15:13 ` Stuart D. Gathman
2011-02-24 15:20 ` Jonathan Tripathy [this message]
2011-02-24 16:41 ` Jonathan Tripathy
2011-02-24 19:15 ` Nataraj
2011-02-24 19:25 ` Les Mikesell
2011-02-24 19:55 ` Stuart D. Gathman
2011-02-24 19:19 ` Stuart D. Gathman
2011-02-24 19:45 ` Stuart D. Gathman
2011-02-24 21:22 ` Jonathan Tripathy
2011-04-05 20:09 ` Jonathan Tripathy
2011-04-05 20:41 ` Stuart D. Gathman
2011-04-05 20:48 ` Jonathan Tripathy
2011-04-05 20:59 ` James Hawtin
2011-04-05 21:36 ` Jonathan Tripathy
2011-04-05 22:42 ` James Hawtin
2011-04-05 22:52 ` Jonathan Tripathy
2011-04-05 23:11 ` James Hawtin
2011-04-05 23:19 ` Jonathan Tripathy
2011-04-05 23:39 ` James Hawtin
2011-04-06 0:00 ` Jonathan Tripathy
2011-04-06 0:08 ` Stuart D. Gathman
2011-04-06 0:14 ` Jonathan Tripathy
2011-04-06 0:16 ` James Hawtin
2011-04-06 0:28 ` Jonathan Tripathy
2011-04-06 0:38 ` Stuart D. Gathman
2011-04-06 0:43 ` Stuart D. Gathman
2011-04-06 1:36 ` James Hawtin
2011-04-06 1:47 ` Jonathan Tripathy
2011-04-06 1:53 ` James Hawtin
2011-04-06 0:47 ` Jonathan Tripathy
2011-04-06 0:42 ` James Hawtin
2011-04-06 0:50 ` Jonathan Tripathy
2011-04-06 1:20 ` James Hawtin
2011-04-06 1:45 ` Jonathan Tripathy
2011-02-23 19:49 ` Nataraj
2011-02-23 19:24 ` Stuart D. Gathman
2011-02-23 19:07 ` [linux-lvm] Problem executing lvm related commands Tinni
2011-02-23 19:33 ` [linux-lvm] Snapshots and disk re-use Phillip Susi
2011-02-23 19:45 ` Stuart D. Gathman
2011-02-23 19:56 ` Nataraj
2011-02-23 13:18 ` Sunil_Gupta2
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