From: Duncan <1i5t5.duncan@cox.net>
To: linux-btrfs@vger.kernel.org
Subject: Re: [PATCH 00/13 v3] Introduce device state 'failed', Hot spare and Auto replace
Date: Mon, 4 Apr 2016 04:45:16 +0000 (UTC) [thread overview]
Message-ID: <pan$5fc01$c48cb58$b5aadf3d$c2af2f78@cox.net> (raw)
In-Reply-To: 20160404020043.47ad35bf@jupiter.sol.kaishome.de
Kai Krakow posted on Mon, 04 Apr 2016 02:00:43 +0200 as excerpted:
> Does this also implement "copy-back" - thus, it returns the hot-spare
> device to global hot-spares when the failed device has been replaced?
I don't believe it does that in this initial implementation, anyway.
There's a number of issues with the initial implementation, including the
fact that the hot-spare is global only and can't be specifically assigned
to a filesystem or set of filesystems, which means, if you have multiple
filesystems using different sized devices, the hot-spares must be sized
to match the largest device they could replace, and thus would be mostly
wasted if they ended up replacing a far smaller device. If the spares
could be associated with specific filesystems, then specifically sized
spares could be associated appropriately, avoiding that waste.
Additionally, it would then be possible to queue up say 20 spares on an
important filesystem, with no spares on another that you'd rather just go
down if a device fails.
So obviously the initial implementation isn't seriously enterprise-ready
and is sub-optimal in many ways, but it's better than what is currently
available (no automated spare handling at all), and an implementation
must start somewhere, so as long as it's designed to be improved and
extended with the missing features over time, as has been indicated, it's
a reasonable first-implementation.
--
Duncan - List replies preferred. No HTML msgs.
"Every nonfree program has a lord, a master --
and if you use the program, he is your master." Richard Stallman
next prev parent reply other threads:[~2016-04-04 4:45 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-04-02 1:30 [PATCH 00/13 v3] Introduce device state 'failed', Hot spare and Auto replace Anand Jain
2016-04-02 1:30 ` [PATCH 01/13] btrfs: Introduce a new function to check if all chunks a OK for degraded mount Anand Jain
2016-04-02 1:30 ` [PATCH 02/13] btrfs: Do per-chunk check for mount time check Anand Jain
2016-04-02 1:30 ` [PATCH 03/13] btrfs: Do per-chunk degraded check for remount Anand Jain
2016-04-02 1:30 ` [PATCH 04/13] btrfs: Allow barrier_all_devices to do per-chunk device check Anand Jain
2016-04-02 1:30 ` [PATCH 05/13] btrfs: Cleanup num_tolerated_disk_barrier_failures Anand Jain
2016-04-02 1:30 ` [PATCH 06/13] btrfs: introduce BTRFS_FEATURE_INCOMPAT_SPARE_DEV Anand Jain
2016-04-02 1:30 ` [PATCH 07/13] btrfs: add check not to mount a spare device Anand Jain
2016-04-02 1:30 ` [PATCH 08/13] btrfs: support btrfs dev scan for " Anand Jain
2016-04-02 1:30 ` [PATCH 09/13] btrfs: provide framework to get and put a " Anand Jain
2016-04-02 1:30 ` [PATCH 10/13] btrfs: introduce helper functions to perform hot replace Anand Jain
2016-04-02 5:40 ` kbuild test robot
2016-04-07 20:00 ` Yauhen Kharuzhy
2016-04-08 3:58 ` Anand Jain
2016-04-08 22:05 ` Yauhen Kharuzhy
2016-04-12 14:16 ` Anand Jain
2016-04-02 1:30 ` [PATCH 11/13] btrfs: introduce device dynamic state transition to offline or failed Anand Jain
2016-04-02 1:30 ` [PATCH 12/13] btrfs: check device for critical errors and mark failed Anand Jain
2016-04-02 1:30 ` [PATCH 13/13] btrfs: check for failed device and hot replace Anand Jain
2016-04-04 0:00 ` [PATCH 00/13 v3] Introduce device state 'failed', Hot spare and Auto replace Kai Krakow
2016-04-04 4:45 ` Duncan [this message]
2016-04-04 6:09 ` Duncan
2016-04-04 20:15 ` Kai Krakow
2016-04-05 3:02 ` Duncan
2016-04-04 6:19 ` Anand Jain
2016-04-04 20:07 ` Kai Krakow
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