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From: "Tomas Dalebjörk" <tomas.dalebjork@gmail.com>
To: Zdenek Kabelac <zkabelac@redhat.com>
Cc: LVM general discussion and development <linux-lvm@redhat.com>
Subject: Re: [linux-lvm] exposing snapshot block device
Date: Mon, 4 Nov 2019 18:28:23 +0100	[thread overview]
Message-ID: <1F8EA03C-9EC5-4006-91A0-4588756F5698@gmail.com> (raw)
In-Reply-To: <992d73bd-259e-a89c-f34f-60388d9e1c5b@redhat.com>

thanks, I understand that meta data blocks needs to be update, that I can understand.
how about the other questions?
like : data write will happen towards which device? cow device or after the copying has been completed to the origin disk?


Skickat från min iPhone

> 4 nov. 2019 kl. 16:04 skrev Zdenek Kabelac <zkabelac@redhat.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 17:28 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
2019-11-04 17:28                           ` Tomas Dalebjörk [this message]
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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