On Sat, Feb 23, 2013 at 01:46:03AM +0100, Fredrik Tolf wrote: > Dear list, > > I'm still in the process of transferring all the data I have to the > btrfs filesystem I have had your help in debugging in a previous > thread, and I have a slight question, if you will humour me. > > I have the data I want to transfer on an old ReiserFS partition, > consisting of 2 mdraid mirrors, one of which consists of two 1.5 TB > disks, and the other of two 3 TB disks. The btrfs I'm copying the > data to consists of two 3 TB disks only that I have put in RAID-1 > mode, and the data on the old filesystem is only slightly larger > than 3 TB. I am now at the point where I have transferred just under > 3 TB. > > If I were transferring the data to a new filesystem on mdraid, the > procedure I would use for that last portion of the data would be to > remove one disk only from either of the old mdraid mirror arrays > (putting that array in degraded mode), and then create a new mirror > in degraded mode with only that disk, add that mirror to the new > filesystem, expand it, copy the last data, and then delete the old > mirrors, moving the rest of the disks to the new filesystem.
That sounds like using seed device, although seed disk is designed for another different purpose. thanks, liubo > > Is there a way to mirror this procedure in btrfs? I'm not yet quite > so familiar with all btrfs concepts that I know quite what I'm > talking about, but I'm guessing that what I want to do is to merely > temporarily set the allocator to allocate new btrfs on a single disk > only, and then add a single disk to the filesystem. And then copy > the rest of the data, abandon the old filesystem and add another > disk and rebalance those singly-allocated extents to RAID-1 mode. > > Have I described a conceptionable idea in saying so? And if so, how > does one actually do that? I don't know if I'm just blind, but I > haven't found any btrfs command to change the allocation algorithm > without having to rebalance the existing data, which seems a bit > unnecessary in this case. > > Thanks for any help you can offer! > > -- > > Fredrik Tolf > -- > To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in > the body of a message to majord...@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
