From: Hendrik Friedel <hendrik@friedels.name>
To: Hugo Mills <hugo@carfax.org.uk>,
Btrfs BTRFS <linux-btrfs@vger.kernel.org>
Subject: Re: How to move a btrfs volume to a smaller disk
Date: Wed, 9 Mar 2016 23:03:53 +0100 [thread overview]
Message-ID: <56E09DC9.7040402@friedels.name> (raw)
In-Reply-To: <20160309215029.GG17196@carfax.org.uk>
Hello Hugo,
thanks for your ultrafast reply.
Unfortunately, it does not work for me:
[root@homeserver mnt2]# btrfs filesystem resize 80G /mnt2/Data_Store/ &&
btrfs replace start /dev/sdb4 /dev/sda4 /mnt2/Data_Store/ -f && btrfs
filesystem resize max /mnt2/Data_Store/
Resize '/mnt2/Data_Store/' of '80G'
ERROR: target device smaller than source device (required 119121379328
bytes)
[root@homeserver mnt2]# btrfs filesystem show /mnt2/Data_Store/
Label: 'Data_Store' uuid: 0ccc1e24-090d-42e2-9e61-d0a1b3101f93
Total devices 1 FS bytes used 47.95GiB
devid 1 size 80.00GiB used 66.03GiB path /dev/sdb4
[root@homeserver mnt2]# lsblk | grep sda4
└─sda4 8:4 0 103.5G 0 part
Greetings,
Hendrik
On 09.03.2016 22:50, Hugo Mills wrote:
> On Wed, Mar 09, 2016 at 10:46:09PM +0100, Hendrik Friedel wrote:
>> Hello,
>>
>> I intend to move this subvolume to a new device.
>> btrfs fi show /mnt2/Data_Store/
>> Label: 'Data_Store' uuid: 0ccc1e24-090d-42e2-9e61-d0a1b3101f93
>> Total devices 1 FS bytes used 47.93GiB
>> devid 1 size 102.94GiB used 76.03GiB path /dev/sdb4
>>
>> (fi usage at the bottom of this message)
>>
>> The new device (sda4) is 8G smaller unfortunately.
>> sda 8:0 0 111.8G 0 disk
>> └─sda4 8:4 0 103.5G 0 part
>> sdb 8:16 0 119.2G 0 disk
>> └─sdb4 8:20 0 111G 0 part /mnt2/Data_Store
>>
>> Thus, btrfs replace does not work
>>
>> What would you suggest now to move the FS (it does contain many subvolumes)?
> btrfs dev resize to shrink it to (slightly smaller than) the
> replacement device, then btrfs replace should work. Then btrfs dev
> resize max to fill up the replacement device completely.
>
> Hugo.
>
>> I tried btrfs send /mnt2/Data_Store/read_only_snapshot/ | btrfs
>> receive /mnt/sda4/
>> but this only created an empty subvolume /mnt/sda4/read_only_snapshot/
>>
>> So, then
>> btrfs device add /dev/sda4 /mnt/Data_Store
>> btrfs balance start /mnt/Data_Store
>> btrfs device remove /dev/sdb4 /mnt/Data_Store
>> ?
>>
>> Or is there a better option?
>>
>> Regards,
>> Hendrik
>>
>>
>> btrfs fi usage /mnt2/Data_Store/
>> Overall:
>> Device size: 102.94GiB
>> Device allocated: 74.03GiB
>> Device unallocated: 28.91GiB
>> Device missing: 0.00B
>> Used: 47.96GiB
>> Free (estimated): 53.24GiB (min: 53.24GiB)
>> Data ratio: 1.00
>> Metadata ratio: 1.00
>> Global reserve: 512.00MiB (used: 0.00B)
>>
>> Data,single: Size:69.00GiB, Used:44.67GiB
>> /dev/sdb4 69.00GiB
>>
>> Metadata,single: Size:5.00GiB, Used:3.29GiB
>> /dev/sdb4 5.00GiB
>>
>> System,single: Size:32.00MiB, Used:16.00KiB
>> /dev/sdb4 32.00MiB
>>
>> Unallocated:
>> /dev/sdb4 28.91GiB
>>
>>
>> ---
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next prev parent reply other threads:[~2016-03-09 22:03 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-03-09 21:46 How to move a btrfs volume to a smaller disk Hendrik Friedel
2016-03-09 21:50 ` Hugo Mills
2016-03-09 22:03 ` Hendrik Friedel [this message]
2016-03-11 3:29 ` Satoru Takeuchi
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