From: Andreas Klauer <Andreas.Klauer@metamorpher.de>
To: Dan Russell <dpr@aol.com>
Cc: linux-raid@vger.kernel.org
Subject: Re: Import/recover RAID6 created with SAS2108?
Date: Wed, 9 Mar 2016 20:27:28 +0100 [thread overview]
Message-ID: <20160309192728.GA3581@EIS> (raw)
In-Reply-To: <ECED3C91-8D12-469E-A9AB-1337292DA216@aol.com>
On Tue, Mar 08, 2016 at 10:20:17PM -0500, Dan Russell wrote:
> The partially-rebuilt drive is sdk, the original “failed” drive is sdag
Best to leave both out if one has outdated and the other only half
the content...
> However fdisk and mdadm are reporting the array is 17.6TB in size, whereas it should be 66TB (24 3TB HDDs RAID6).
I reproduced your commands using tmpfs based loop devices and it gives me
the same problem. The RAID size is only 16 TiB. It seems to be hitting a
limit somewhere.
Your /dev/mapper/sdx are snapshot/overlays, I hope?
DDF metadata seems to be located at the end of the device, so you could try
your luck with mdadm 1.0 metadata instead; that gives me a RAID of a size
closer to home.
# mdadm --create /dev/md42 --assume-clean --metadata=1.0 --level=6 --raid-devices=24 --chunk=64 /dev/loop{0..23}
# fdisk -l /dev/md42
Disk /dev/md42: 60 TiB, 65999996846080 bytes, 128906243840 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 65536 bytes / 1441792 bytes
It wastes some sectors at the end though, not sure if more or less
than what DDF uses for metadata. You might have to add some empty
space to your device mappings to get a full view.
Regards
Andreas Klauer
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next prev parent reply other threads:[~2016-03-09 19:27 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-03-06 21:37 Import/recover RAID6 created with SAS2108? Dan Russell
2016-03-07 21:50 ` Andreas Klauer
2016-03-09 3:20 ` Dan Russell
2016-03-09 19:27 ` Andreas Klauer [this message]
2016-03-09 20:53 ` Dan Russell
2016-03-10 7:02 ` NeilBrown
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