Hi, First of Neil thanks for the answer. Stan, thanks for your suggestions. I'm only using WD RE4 devices since I find anything less is to unreliable. (otherwise I agree, there is many consumer drives that i would not even let my data go near) I have Backups of the things I can't lose. A pair of 4TB with no redundancy - no thanks. Allways keep important data on atleast 2 places. I would never kill one of those ;) Thats why I do the resize, I risk the data, but don't kill it. On Wed, Jul 31, 2013 at 10:18 AM, Stan Hoeppner <stan@xxxxxxxxxxxxxxxxx> wrote: > On 7/30/2013 10:28 PM, NeilBrown wrote: >> On Wed, 31 Jul 2013 01:33:46 +0200 Christian Nilsson <nikize@xxxxxxxxx> wrote: > ... >>> but just to explain: >>> I have a 9 devices in a RAID5 >>> 6 of these are now 2TB disks (I really love hot replace!) >>> while the other 3 are still 1TB disks >>> >>> I would now like to grow the array to 6x2TB instead of the present 9x1TB. >>> >>> Is this possible and I just can't find how, or have there just been to >>> many other great features instead? >>> (I have started a ext4 offline shrink.. but it is a real pain.) >> >> Sorry, but this function hasn't been implemented yet. > > > Christian, there is an old storage industry axiom that goes something > like "one can only afford as much storage as one can afford to back up". > > This says that you need sufficient storage media to backup the files > residing in the filesystem on your primary storage array. It seems > clear that you currently have no such backup media nor strategy. The > only suitable consumer media with sufficient capacity would be more hard > drives. > > I'd suggest acquiring a pair of 4TB drives, or 3x3TB depending on price > break, to use from this point forward strictly as backup media. Create > an md linear array of the new drives, format it with XFS. Look at the > directory structure of your existing array and based on that fire off > multiple 'cp -a' commands in parallel to copy the dirs and files over. > This method will get all backup disks in play due to AG parallelism in > XFS, increasing throughput, and decreasing total backup time. > > Once you're backed up, blow away the original array and create a new > one, but I suggest using your 6x2TB disks in RAID6 instead of RAID5. > IMO, and that of many others here, RAID5 with many muti-TB disks is > simply too prone to double disk failure during rebuilds/reshapes, silent > data corruption due to the RAID5 write hole, etc, especially with > consumer quality drives. With many hi-cap consumer drives, RAID5 is a > time bomb. > > So in the end you'll have 1TB less raw capacity, 8TB vs 9TB, but you'll > be protected by double parity RAID6 and you'll have sufficient backup > device capacity to safeguard your primary array, even if it's completely > full. Once everything is migrated you'll want to implement a scheduled > backup strategy using rsync or something similar, so you're > automatically backing up new files and those that have changed, on a > daily schedule. Nobody needs a backup until they need it. Don't find > yourself needing one and not having it. > > -- > Stan > -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
