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From: Zdenek Kabelac <zkabelac@redhat.com>
To: "Tomas Dalebjörk" <tomas.dalebjork@gmail.com>
Cc: LVM general discussion and development <linux-lvm@redhat.com>
Subject: Re: [linux-lvm] exposing snapshot block device
Date: Mon, 4 Nov 2019 16:04:34 +0100	[thread overview]
Message-ID: <992d73bd-259e-a89c-f34f-60388d9e1c5b@redhat.com> (raw)
In-Reply-To: <CACrcyfJxYvr7BC6Srts1bnNWLxsme8d3hjEQqYQyBz9sqbNp6g@mail.gmail.com>

Dne 04. 11. 19 v 15:40 Tomas Dalebjörk napsal(a):
> Thanks for feedback.
> 
>

> Scenario 2: A write comes want to write block LP 100, but lvconvert has not 
> yet copied that LP block (yes, I do understand that origin is hidden now)
> Will lvconvery prioritize to copy data from /dev/vg00/lv00-snap to 
> /dev/vg00/lv00 for that block, and let the requestor write the changes 
> directly on the origin after the copying has been performed?
> Or will the write be blocked until lvconvert has finished the copying of the 
> requested block, and than a write can be accepted to the origin?
> Or where will the changes be written?

Since the COW device contains not only 'data' but also 'metadata'  blocks
and during the 'merge' it's being updated so it 'knows' which data has
been already merged back to origin (in other words during the merge the usage 
of COW is being reduced towards 0)  - I assume your 'plan' stops right here
and there is not much point to explore how much sub-optimal the rest of 
merging process is  (and as said - primary aspect was robustness - so if there 
is crash in any moment in time - data remain correct)

Regards

Zdenek

  reply	other threads:[~2019-11-04 15:04 UTC|newest]

Thread overview: 53+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-10-22 10:47 [linux-lvm] exposing snapshot block device Dalebjörk, Tomas
2019-10-22 13:57 ` Zdenek Kabelac
2019-10-22 15:29   ` Dalebjörk, Tomas
2019-10-22 15:36     ` Zdenek Kabelac
2019-10-22 16:13       ` Dalebjörk, Tomas
2019-10-23 10:26         ` Zdenek Kabelac
2019-10-23 10:56           ` Tomas Dalebjörk
2019-10-22 16:15       ` Stuart D. Gathman
2019-10-22 17:02         ` Tomas Dalebjörk
2019-10-22 21:38         ` Gionatan Danti
2019-10-22 22:53           ` Stuart D. Gathman
2019-10-23  6:58             ` Gionatan Danti
2019-10-23 10:06               ` Tomas Dalebjörk
2019-10-23 10:12             ` Zdenek Kabelac
2019-10-23 10:46         ` Zdenek Kabelac
2019-10-23 11:08           ` Gionatan Danti
2019-10-23 11:24             ` Tomas Dalebjörk
2019-10-23 11:26               ` Tomas Dalebjörk
2019-10-24 16:01               ` Zdenek Kabelac
2019-10-25 16:31                 ` Tomas Dalebjörk
2019-11-04  5:54                   ` Tomas Dalebjörk
2019-11-04 10:07                     ` Zdenek Kabelac
2019-11-04 14:40                       ` Tomas Dalebjörk
2019-11-04 15:04                         ` Zdenek Kabelac [this message]
2019-11-04 17:28                           ` Tomas Dalebjörk
2019-11-05 16:24                             ` Zdenek Kabelac
2019-11-05 16:40                         ` Mikulas Patocka
2019-11-05 20:56                           ` Tomas Dalebjörk
2019-11-06  9:22                             ` Zdenek Kabelac
2019-11-07 16:54                             ` Mikulas Patocka
2019-11-07 17:29                               ` Tomas Dalebjörk
2020-09-04 12:09                                 ` Tomas Dalebjörk
2020-09-04 12:37                                   ` Zdenek Kabelac
2020-09-07 13:09                                   ` Mikulas Patocka
2020-09-07 14:14                                     ` Dalebjörk, Tomas
2020-09-07 14:17                                       ` Zdenek Kabelac
2020-09-07 16:34                                         ` Tomas Dalebjörk
2020-09-07 16:42                                           ` Zdenek Kabelac
2020-09-07 17:37                                             ` Tomas Dalebjörk
2020-09-07 17:50                                               ` Zdenek Kabelac
2020-09-08 12:32                                                 ` Dalebjörk, Tomas
2020-09-07 19:56                                             ` Tomas Dalebjörk
2020-09-07 20:22                                               ` Tomas Dalebjörk
2020-09-07 21:02                                               ` Tomas Dalebjörk
2019-10-23 12:12             ` Ilia Zykov
2019-10-23 12:20             ` Ilia Zykov
2019-10-23 13:05               ` Zdenek Kabelac
2019-10-23 14:40                 ` Gionatan Danti
2019-10-23 15:46                   ` Ilia Zykov
2019-10-23 12:59             ` Zdenek Kabelac
2019-10-23 14:37               ` Gionatan Danti
2019-10-23 15:37                 ` Zdenek Kabelac
2019-10-23 17:16                   ` Gionatan Danti

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