From: David Brown <david@westcontrol.com>
To: NeilBrown <neilb@suse.de>
Cc: keld@keldix.com, linux-raid@vger.kernel.org
Subject: Re: [md PATCH 15/23] md/raid10 - support resizing some RAID10 arrays.
Date: Wed, 14 Mar 2012 08:51:44 +0100 [thread overview]
Message-ID: <4F604E10.20605@westcontrol.com> (raw)
In-Reply-To: <20120314172712.3aa9310a@notabene.brown>
On 14/03/2012 07:27, NeilBrown wrote:
> On Wed, 14 Mar 2012 07:17:46 +0100 keld@keldix.com wrote:
>
>> Hi Neil
>>
>> What is the problem with adding space to the 'far' layout?
>>
>> I would think you could just create the new array part 1 from the
>> old array part 2, and then sync the new array part 2 with the new
>> array part 1. (in the case of a far=2 array, for n>2 similar
>> constructs would apply).
>
> If I understand your proposal correctly, you would lose redundancy
> during the process, which is not acceptable.
>
That's how I understood the suggestion too. And in some cases, that
might be a good choice for the user - if they have good backups, they
might be happy to risk such a re-shape. Of course, they would have to
use the "--yes-I-really-understand-the-risks" flag to mdadm, but other
than that it should be pretty simple to implement.
For a safe re-shape of raid10, you would need to move the "far" copy
backwards to the right spot on the growing disk (or forwards if you are
shrinking the array). It could certainly be done safely, and would be
very useful for users, but it is not quite as simple as an unsafe re-size.
mvh.,
David
> If I don't understand properly - please explain in a bit more
> detail.
>
> Thanks, NeilBrown
>
next prev parent reply other threads:[~2012-03-14 7:51 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-03-14 4:40 [md PATCH 00/23] md patches heading for 3.4 NeilBrown
2012-03-14 4:40 ` [md PATCH 03/23] md/raid5: removed unused 'added_devices' variable NeilBrown
2012-03-14 4:40 ` [md PATCH 06/23] md: allow last device to be forcibly removed from RAID1/RAID10 NeilBrown
2012-03-14 4:40 ` [md PATCH 01/23] md/raid5: make sure reshape_position is cleared on error path NeilBrown
2012-03-14 4:40 ` [md PATCH 05/23] md/raid5: use atomic_dec_return() instead of atomic_dec() and atomic_read() NeilBrown
2012-03-14 4:40 ` [md PATCH 02/23] md/raid10: remove unnecessary smp_mb() from end_sync_write NeilBrown
2012-03-14 4:40 ` [md PATCH 04/23] md: Use existed macros instead of numbers NeilBrown
2012-03-14 4:40 ` [md PATCH 12/23] md: add proper merge_bvec handling to RAID0 and Linear NeilBrown
2012-03-14 4:40 ` [md PATCH 09/23] md/bitmap: ensure to load bitmap when creating via sysfs NeilBrown
2012-03-14 4:40 ` [md PATCH 14/23] md/raid1: handle merge_bvec_fn in member devices NeilBrown
2012-03-14 4:40 ` [md PATCH 08/23] md: don't set md arrays to readonly on shutdown NeilBrown
2012-04-18 15:37 ` Alexander Lyakas
2012-04-18 17:44 ` Paweł Brodacki
2012-04-18 20:53 ` Alexander Lyakas
2012-04-18 22:48 ` NeilBrown
2012-04-19 9:11 ` Alexander Lyakas
2012-04-19 9:57 ` NeilBrown
2012-04-20 11:30 ` Paweł Brodacki
2012-04-20 12:01 ` NeilBrown
2012-04-21 15:18 ` Paweł Brodacki
2012-04-21 20:42 ` NeilBrown
2012-04-30 10:32 ` Paweł Brodacki
2012-04-20 16:26 ` John Robinson
2012-03-14 4:40 ` [md PATCH 10/23] md/raid1, raid10: avoid deadlock during resync/recovery NeilBrown
2012-03-14 4:40 ` [md PATCH 11/23] md: tidy up rdev_for_each usage NeilBrown
2012-03-14 4:40 ` [md PATCH 13/23] md/raid10: handle merge_bvec_fn in member devices NeilBrown
2012-03-14 4:40 ` [md PATCH 07/23] md: allow re-add to failed arrays NeilBrown
2012-03-14 4:40 ` [md PATCH 19/23] md/bitmap: remove some pointless locking NeilBrown
2012-03-14 4:40 ` [md PATCH 17/23] md/bitmap: move printing of bitmap status to bitmap.c NeilBrown
2012-03-14 4:40 ` [md PATCH 21/23] md/bitmap: discard CHUNK_BLOCK_SHIFT macro NeilBrown
2012-03-14 4:40 ` [md PATCH 18/23] md/bitmap: change a 'goto' to a normal 'if' construct NeilBrown
2012-03-14 4:40 ` [md PATCH 22/23] md: fix clearing of the 'changed' flags for the bad blocks list NeilBrown
2012-03-14 4:40 ` [md PATCH 15/23] md/raid10 - support resizing some RAID10 arrays NeilBrown
2012-03-14 6:17 ` keld
2012-03-14 6:27 ` NeilBrown
2012-03-14 7:51 ` David Brown [this message]
2012-03-14 8:32 ` NeilBrown
2012-03-14 10:20 ` David Brown
2012-03-14 12:37 ` keld
2012-03-14 4:40 ` [md PATCH 20/23] md/bitmap: remove unnecessary indirection when allocating NeilBrown
2012-03-14 4:40 ` [md PATCH 16/23] md/bitmap: remove some unused noise from bitmap.h NeilBrown
2012-03-14 4:40 ` [md PATCH 23/23] md: Add judgement bb->unacked_exist in function md_ack_all_badblocks() NeilBrown
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=4F604E10.20605@westcontrol.com \
--to=david@westcontrol.com \
--cc=keld@keldix.com \
--cc=linux-raid@vger.kernel.org \
--cc=neilb@suse.de \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).