I have 2 ReadyNAS units, one is an Ultra 6 Plus and the second is the Ultra 6 Pro. Both have 3x 2TB WD Black WD2002FAEX in an Xraid2 format (2x2TB = 4TB + 1x 2TB Redundancy)
Western Digital have just released their new 3TB Red WD30EFRX, which has a similar price to the hard drives I use already.
First Question: Could I replace drive 2 (the 2TB redundant drive) with the new 3TB drive, and migrate the HDD that was in drive 2 to drive 4? This would allow me to increase my capacity by 2TB, whilst allow for future proofing the unit as the new 3TB drives become the standard.
So the new lay out would be: Current layout: Drive 1: 2TB Xraid2 Drive 2: 3TB Xraid2 (Redundant) Drive 3: 2TB Xraid2 Drive 4: 2TB Xraid2 Drive 5: Empty Drive 6: Empty (6TB Capacity + 2TB Redundancy)
Second Question: After the stage above has been completed could I replace drive 1 with the new 3TB drive, and migrate the HDD that was in drive 1 to drive 5? Hypothetically this should increase my overall capacity by 3TB as the redundant drive would already be at 3TB.
So the ending state of the unit would be: Drive 1: 3TB Xraid2 Drive 2: 3TB Xraid2 (Redundant) Drive 3: 2TB Xraid2 Drive 4: 2TB Xraid2 Drive 5: 2TB Xraid2 Drive 6: Empty (9TB Capacity + 3TB Redundancy)
This end result looks to be an acceptable state of Xraid2 (http://www.readynas.com/?p=656), but the steps to get there are not standard and don’t look to have been practiced. But this would save me money in the long run.
Has anyone had any experience trying something like this before?
Don't rearrange the disks. You need to add the lower capacity disks first. Put the 3TB disks in the empty slots if you want maximum storage. Also note that there's an 8TB online expansion limit over the life of the volume e.g. if your volume started out at 3.6TB you can't expand beyond 11.6TB.
The normal way to do this would be to simply insert the two 3 TB drives into slots 4 and 5. There is no technical need to "migrate", or to put the 3 TB drives in the first two slots. The migration approach rebuilds the array needlessly (and isn't quite as safe, since you lose redundancy when you take out the existing drives).
If for some reason you want to do the migration, you should be able to. Though it might be safer if you delete the partitions on the old 2 TB drives (using your PC) before you reinsert them. Occasionally you might see a "corrupt root" if you reinstall a disk that was previously used in an a readynas.
Also, with Xraid2, the redundancy is spread across all the drives, so there is nothing uniquely "redundant" about drive 2.
mdgm: I never knew about that 8TB expansion limit, is that a limit of the Unit or Xraid2? and as the first HDD added to the "life" of the volume was 2TB does that mean my limit is 2TB + 8TB = 10TB limit? and is the Redundancy included as an expansion?
StephenB: Ah that is good news, the way I saw it describe made it sound like drive two was my redundacy, and not by having it split across all the HDD. So I should be able to keep my resilience, simply by adding my 3TB drive. So if I have this right, by adding 1x 3TB should increase my capcity (regardless of where it is put) by 2TB and when I add my second 3TB HDD I get the full 3TB?
If you started off with one or two disks you would have had a volume of roughly 1.8TB so you could expand to roughly 9.8TB. So depending what you started off with you might be better to backup your data, do a factory default (wipes all data, settings, everything) with your disks in place then restore data from backup
Yes. You can put the first new 3TB drive in either bay. Then once that's synced and expansion has taken place put the other 3TB drive in.
mdgm:I never knew about that 8TB expansion limit, is that a limit of the Unit or Xraid2? and as the first HDD added to the "life" of the volume was 2TB does that mean my limit is 2TB + 8TB = 10TB limit? and is the Redundancy included as an expansion?
there are two limits, and both apply to the available capacity (not including the redundancy). One is that you can't expand beyond 16 TB total. The second is that you can't expand more than 8 TB from the capacity at your initial install/last factory default. If you started with a single 2 TB installed, then your ceiling is 10 TB. Your new configuration has 9 TB total available space, so your new configuration is still just under the limit.
The way to overcome both these limits is to do a factory default with all your disks in place. This deletes all your data, including your configuration (add-ons, users, share definitions, etc). So you need to reload everything from backup. The more data you have, the more time consuming this becomes. So as mdgm suggests, it might be easier to do it sooner. Though I think I would wait until you install the 2nd 3 TB drive. At that point you have about 9 TB available space, so defaulting then allows you to expand in the future up to the full 16 TB ceiling.
Both of these are OS (linux) limitations.
coolsnaz wrote:
StephenB: Ah that is good news, the way I saw it describe made it sound like drive two was my redundacy, and not by having it split across all the HDD. So I should be able to keep my resilience, simply by adding my 3TB drive. So if I have this right, by adding 1x 3TB should increase my capcity (regardless of where it is put) by 2TB and when I add my second 3TB HDD I get the full 3TB?
Yes. So this expansion is easier than you were thinking.
I intend on moving one of the units off site, so I think getting the 3TBx HDD in asap would be preferable as I would be in a convenient position to do one upgrade including a full factory reset and rebuild. Then do a full Rsync backup over the LAN (rather than WAN), and then do the same factory reset and rebuild on the second unit. And as I am unlikely to fill the units with HDD larger than 3TB each, I shouldn’t go over 15TB with the 3TB redundancy. Which is under the 16TB Linux limitation!
Thank you both for all your help, it has been very informative and has helped my design a tremendous amount!
BTW, you can save your NAS configuration to your PC, and restore it after the default procedure, which speeds things up a little. If you do this, be careful to re-install any third party add-ons before you restore the configuration. After the config is restored, you can restore the data. Generally I use NFS initially because it is a lot faster. Then I edit the backup jobs to use rsync, and run them again (just to be sure everything is synced).
Hi Guys, Just in case anyone was wondering the first stage of the upgrade went perfectly. Old layout: Drive 1: 2TB Xraid2 - WD2002FAEX Drive 2: 2TB Xraid2 - WD2002FAEX Drive 3: 2TB Xraid2 - WD2002FAEX Drive 4: Empty Drive 5: Empty Drive 6: Empty (6TB Capacity + NO Redundancy)
So basically the new 3TB drive gave me drive resilience, and I was able to do a complete factory reset as well. And despite the heat we have been getting the unit has been running perfectly.
