RAID1 migrate to bigger disks

RAID1 migrate to bigger disks

[Daniel Pocock]

I've got a RAID1 on two 1TB partitions, /dev/sda3 and /dev/sdb3

I'm adding two new disks, they will have bigger partitions /dev/sdc3 and
/dev/sdd3

I'd like the BtrFs to migrate from the old partitions to the new ones as
safely and quickly as possible and if it is reasonable to do so, keeping
it online throughout the migration.

Should I do the following:

btrfs device add /dev/sdc3 /dev/sdd3 /mnt/btrfs0
btrfs device delete /dev/sda3 /dev/sdb3 /mnt/btrfs0

or should I do it this way:

btrfs device add /dev/sdc3 /mnt/btrfs0
btrfs device delete /dev/sda3 /mnt/btrfs0
btrfs device add /dev/sdd3 /mnt/btrfs0
btrfs device delete /dev/sdb3 /mnt/btrfs0

or is there some other way to go about it?

Re: RAID1 migrate to bigger disks

[Hugo Mills]

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On Sat, Jan 24, 2015 at 03:32:44PM +0100, Daniel Pocock wrote:
> 
> 
> 
> I've got a RAID1 on two 1TB partitions, /dev/sda3 and /dev/sdb3
> 
> I'm adding two new disks, they will have bigger partitions /dev/sdc3 and
> /dev/sdd3
> 
> I'd like the BtrFs to migrate from the old partitions to the new ones as
> safely and quickly as possible and if it is reasonable to do so, keeping
> it online throughout the migration.
> 
> Should I do the following:
> 
> btrfs device add /dev/sdc3 /dev/sdd3 /mnt/btrfs0
> btrfs device delete /dev/sda3 /dev/sdb3 /mnt/btrfs0
> 
> or should I do it this way:
> 
> btrfs device add /dev/sdc3 /mnt/btrfs0
> btrfs device delete /dev/sda3 /mnt/btrfs0
> btrfs device add /dev/sdd3 /mnt/btrfs0
> btrfs device delete /dev/sdb3 /mnt/btrfs0
> 
> or is there some other way to go about it?

btrfs replace start /dev/sda3 /dev/sdc3 /mountpoint
btrfs fi resize 3:max /mountpoint
btrfs replace start /dev/sdb3 /dev/sdd3 /mountpoint
btrfs fi resize 4:max /mountpoint

   The 3 and 4 in the resize commands should be the devid of the
newly-added device.

   Hugo.

-- 
Hugo Mills             | I'll take your bet, but make it ten thousand francs.
hugo@... carfax.org.uk | I'm only a _poor_ corrupt official.
http://carfax.org.uk/  |
PGP: 65E74AC0          |                              Capt. Renaud, Casablanca

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Re: RAID1 migrate to bigger disks

[Daniel Pocock]

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Hash: SHA256



On 24/01/15 15:36, Hugo Mills wrote:
> On Sat, Jan 24, 2015 at 03:32:44PM +0100, Daniel Pocock wrote:
>> 
>> 
>> 
>> I've got a RAID1 on two 1TB partitions, /dev/sda3 and /dev/sdb3
>> 
>> I'm adding two new disks, they will have bigger partitions
>> /dev/sdc3 and /dev/sdd3
>> 
>> I'd like the BtrFs to migrate from the old partitions to the new
>> ones as safely and quickly as possible and if it is reasonable to
>> do so, keeping it online throughout the migration.
>> 
>> Should I do the following:
>> 
>> btrfs device add /dev/sdc3 /dev/sdd3 /mnt/btrfs0 btrfs device
>> delete /dev/sda3 /dev/sdb3 /mnt/btrfs0
>> 
>> or should I do it this way:
>> 
>> btrfs device add /dev/sdc3 /mnt/btrfs0 btrfs device delete
>> /dev/sda3 /mnt/btrfs0 btrfs device add /dev/sdd3 /mnt/btrfs0 
>> btrfs device delete /dev/sdb3 /mnt/btrfs0
>> 
>> or is there some other way to go about it?
> 
> btrfs replace start /dev/sda3 /dev/sdc3 /mountpoint btrfs fi resize
> 3:max /mountpoint btrfs replace start /dev/sdb3 /dev/sdd3
> /mountpoint btrfs fi resize 4:max /mountpoint
> 
> The 3 and 4 in the resize commands should be the devid of the 
> newly-added device.

Thanks for the fast reply

In the event of power failure, can I safely shutdown the server during
this operation and resume after starting again?

I get more than 2 hours runtime from the UPS but I suspect that
migrating 1TB will take at least 12 hours.


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Re: RAID1 migrate to bigger disks

[Martin Steigerwald]

Am Samstag, 24. Januar 2015, 15:46:22 schrieb Daniel Pocock:
> On 24/01/15 15:36, Hugo Mills wrote:
> > On Sat, Jan 24, 2015 at 03:32:44PM +0100, Daniel Pocock wrote:
> >> I've got a RAID1 on two 1TB partitions, /dev/sda3 and /dev/sdb3
> >> 
> >> I'm adding two new disks, they will have bigger partitions
> >> /dev/sdc3 and /dev/sdd3
> >> 
> >> I'd like the BtrFs to migrate from the old partitions to the new
> >> ones as safely and quickly as possible and if it is reasonable to
> >> do so, keeping it online throughout the migration.
> >> 
> >> Should I do the following:
> >> 
> >> btrfs device add /dev/sdc3 /dev/sdd3 /mnt/btrfs0 btrfs device
> >> delete /dev/sda3 /dev/sdb3 /mnt/btrfs0
> >> 
> >> or should I do it this way:
> >> 
> >> btrfs device add /dev/sdc3 /mnt/btrfs0 btrfs device delete
> >> /dev/sda3 /mnt/btrfs0 btrfs device add /dev/sdd3 /mnt/btrfs0
> >> btrfs device delete /dev/sdb3 /mnt/btrfs0
> >> 
> >> or is there some other way to go about it?
> > 
> > btrfs replace start /dev/sda3 /dev/sdc3 /mountpoint btrfs fi resize
> > 3:max /mountpoint btrfs replace start /dev/sdb3 /dev/sdd3
> > /mountpoint btrfs fi resize 4:max /mountpoint
> > 
> > The 3 and 4 in the resize commands should be the devid of the
> > newly-added device.
> 
> Thanks for the fast reply
> 
> In the event of power failure, can I safely shutdown the server during
> this operation and resume after starting again?
> 
> I get more than 2 hours runtime from the UPS but I suspect that
> migrating 1TB will take at least 12 hours.

You can at least cancel the replacing:

merkaba:~> btrfs replace --help
usage: btrfs replace <command> [<args>]

    btrfs replace start [-Bfr] <srcdev>|<devid> <targetdev> <mount_point>
        Replace device of a btrfs filesystem.
    btrfs replace status [-1] <mount_point>
        Print status and progress information of a running device replace
    btrfs replace cancel <mount_point>
        Cancel a running device replace operation.

I thought you could resume it then later, but I don't see this. The man 
page doesn't see it either.

-- 
Martin 'Helios' Steigerwald - http://www.Lichtvoll.de
GPG: 03B0 0D6C 0040 0710 4AFA  B82F 991B EAAC A599 84C7

RE: RAID1 migrate to bigger disks

[Paul Jones]

> -----Original Message-----
> From: linux-btrfs-owner@vger.kernel.org [mailto:linux-btrfs-
> owner@vger.kernel.org] On Behalf Of Daniel Pocock
> Sent: Sunday, 25 January 2015 1:46 AM
> To: Hugo Mills; linux-btrfs@vger.kernel.org
> Subject: Re: RAID1 migrate to bigger disks
> 
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA256
> 
> 
> 
> On 24/01/15 15:36, Hugo Mills wrote:
> > On Sat, Jan 24, 2015 at 03:32:44PM +0100, Daniel Pocock wrote:
> >>
> >>
> >>
> >> I've got a RAID1 on two 1TB partitions, /dev/sda3 and /dev/sdb3
> >>
> >> I'm adding two new disks, they will have bigger partitions
> >> /dev/sdc3 and /dev/sdd3
> >>
> >> I'd like the BtrFs to migrate from the old partitions to the new ones
> >> as safely and quickly as possible and if it is reasonable to do so,
> >> keeping it online throughout the migration.
> >>
> >> Should I do the following:
> >>
> >> btrfs device add /dev/sdc3 /dev/sdd3 /mnt/btrfs0 btrfs device delete
> >> /dev/sda3 /dev/sdb3 /mnt/btrfs0
> >>
> >> or should I do it this way:
> >>
> >> btrfs device add /dev/sdc3 /mnt/btrfs0 btrfs device delete
> >> /dev/sda3 /mnt/btrfs0 btrfs device add /dev/sdd3 /mnt/btrfs0 btrfs
> >> device delete /dev/sdb3 /mnt/btrfs0
> >>
> >> or is there some other way to go about it?
> >
> > btrfs replace start /dev/sda3 /dev/sdc3 /mountpoint btrfs fi resize
> > 3:max /mountpoint btrfs replace start /dev/sdb3 /dev/sdd3 /mountpoint
> > btrfs fi resize 4:max /mountpoint
> >
> > The 3 and 4 in the resize commands should be the devid of the
> > newly-added device.
> 
> Thanks for the fast reply
> 
> In the event of power failure, can I safely shutdown the server during this
> operation and resume after starting again?
> 
> I get more than 2 hours runtime from the UPS but I suspect that migrating
> 1TB will take at least 12 hours.

I know that removing a device can be interrupted safely by a reboot - I do it all the time as there is no cancel option for removal. It seems to operate the same way balance does, by moving data around, and when there is nothing left on the disk it is removed and de-associated.

Paul.