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From: Anand Jain <anand.jain@oracle.com>
To: Qu Wenruo <quwenruo@cn.fujitsu.com>
Cc: linux-btrfs@vger.kernel.org
Subject: Re: [PATCH 00/15] btrfs: Hot spare and Auto replace
Date: Fri, 13 Nov 2015 18:18:46 +0800	[thread overview]
Message-ID: <5645B906.8030402@oracle.com> (raw)
In-Reply-To: <5643F62D.6050703@cn.fujitsu.com>



Thanks for the comments.

> Let's take the following example:
>
> 1) 2 RAID1 + 1 spare
>     (A + B) + C
>
> 2) 3 RAID1
>     (A + B + C)

> At least in normal operation case, case 1) makes device C useless, and

  Yes.

> For case 2), we can just relocate and recover the bad chunks in B.
> It it should only need to copy 6G data.

  Case 2 is Wrong in the context of spare.

  Unless space usage is limited to 1/3 of total space.
  But when you do that, case 1 drawback will equally apply
  to case 2 as well.


 > It it should only need to copy 6G data.

   Its true as long as you don't replace the failed B
   and bring the configuration to its original. However
   when you do that,  Data  moved will be more than case 1.
   So this is not fully correct.

Thanks, Anand

  parent reply	other threads:[~2015-11-13 10:19 UTC|newest]

Thread overview: 43+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-11-09 10:56 [PATCH 00/15] btrfs: Hot spare and Auto replace Anand Jain
2015-11-09 10:56 ` [PATCH 01/15] btrfs: Introduce a new function to check if all chunks a OK for degraded mount Anand Jain
2015-11-09 10:56 ` [PATCH 02/15] btrfs: Do per-chunk check for mount time check Anand Jain
2015-11-09 10:56 ` [PATCH 03/15] btrfs: Do per-chunk degraded check for remount Anand Jain
2015-11-09 10:56 ` [PATCH 04/15] btrfs: Allow barrier_all_devices to do per-chunk device check Anand Jain
2015-11-09 10:56 ` [PATCH 05/15] btrfs: optimize btrfs_check_degradable() for calls outside of barrier Anand Jain
2015-11-09 10:56 ` [PATCH 06/15] btrfs: Cleanup num_tolerated_disk_barrier_failures Anand Jain
2015-12-05  7:16   ` Qu Wenruo
2015-11-09 10:56 ` [PATCH 07/15] btrfs: introduce device dynamic state transition to offline or failed Anand Jain
2015-11-09 10:56 ` [PATCH 08/15] btrfs: check device for critical errors and mark failed Anand Jain
2015-11-09 10:56 ` [PATCH 09/15] btrfs: block incompatible optional features at scan Anand Jain
2015-11-09 10:56 ` [PATCH 10/15] btrfs: introduce BTRFS_FEATURE_INCOMPAT_SPARE_DEV Anand Jain
2015-11-09 10:56 ` [PATCH 11/15] btrfs: add check not to mount a spare device Anand Jain
2015-11-09 10:56 ` [PATCH 12/15] btrfs: support btrfs dev scan for " Anand Jain
2015-11-09 10:56 ` [PATCH 13/15] btrfs: provide framework to get and put a " Anand Jain
2015-11-09 10:56 ` [PATCH 14/15] btrfs: introduce helper functions to perform hot replace Anand Jain
2015-11-09 10:56 ` [PATCH 15/15] btrfs: check for failed device and " Anand Jain
2015-11-09 10:58 ` [PATCH 0/4] btrfs-progs: Hot spare and Auto replace Anand Jain
2015-11-09 10:58   ` [PATCH 1/4] btrfs-progs: Introduce BTRFS_FEATURE_INCOMPAT_SPARE_DEV SB flags Anand Jain
2015-11-09 10:58   ` [PATCH 2/4] btrfs-progs: Introduce btrfs spare subcommand Anand Jain
2015-11-09 10:58   ` [PATCH 3/4] btrfs-progs: add fi show for spare Anand Jain
2015-11-09 10:58   ` [PATCH 4/4] btrfs-progs: add global spare device list to filesystem show Anand Jain
2015-11-09 14:09 ` [PATCH 00/15] btrfs: Hot spare and Auto replace Austin S Hemmelgarn
2015-11-09 21:29   ` Duncan
2015-11-10 12:13     ` Austin S Hemmelgarn
2015-11-13 10:17       ` Anand Jain
2015-11-13 12:25         ` Austin S Hemmelgarn
2015-11-15 18:10         ` Christoph Anton Mitterer
2015-11-12  2:15 ` Qu Wenruo
2015-11-12  6:46   ` Duncan
2015-11-12 13:04   ` Austin S Hemmelgarn
2015-11-13  1:07     ` Qu Wenruo
2015-11-13 10:20       ` Anand Jain
2015-11-14  0:54         ` Qu Wenruo
2015-11-16 13:39           ` Austin S Hemmelgarn
2015-11-12 19:08   ` Goffredo Baroncelli
2015-11-13 10:18   ` Anand Jain [this message]
2015-11-12 19:21 ` Goffredo Baroncelli
2015-11-13 10:20   ` Anand Jain
2015-11-14 11:05     ` Goffredo Baroncelli
2015-11-16 13:41 ` Austin S Hemmelgarn
2015-11-16 22:07   ` Anand Jain
2015-11-17 12:28     ` Austin S Hemmelgarn

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