RAID Level X-2, 3 TB, Ultra 6 Pro, Usable Space

[gsinha]

All:

I have 6 3 TB Hitachi drives in an Ultra 6 Pro, firmware 4.2.19. Trying to understand how much total usable space i should get, the NAS is re-syncing right now but shows 11,856 GB of total space. Is this what I should expect?

I've had to do a few reboots and have received log file messages saying 'Volume Expansion Failed'. This is after a resync that seemed to hang at the 100% complete mark and required a power shutdown.

Your help appreciated and thanking you in advance.

[PapaBear]

If you are using single redundancy, the effective net storage would be approximately 2790GB x 5 disks (the sixth is used for redundancy) which is approx 13,950GB which would probably show up as 13TB on the front panel. If you are using dual redundancy, the effective net storage would be approximately 2,790GB x 4 disks (the other 2 used for redundancy) which is approximately 11,160GB which would show up on the front panel as 11TB. I would wait until the unit is completely finished synching before checking the available volume.

Remember that no single storage unit is to ever be used without a backup of your data. Murphy is always lurking.

[gsinha]

Thanks.

The resync appears to have gone OK and the final result shows 11,856 GB of usable space (assuming that is what I should get using dual redundancy). One odd thing is that I keep getting 'Volume Expansion Failed' messages after a clean shutdown and reboot. Everything seems to be working OK so can't really tell what is going on.

[jacw]

I have a similar issue on my Ultra 6. I received "Volume expansion failed" message when adding my 5th 3TB drive, but the Volumes tab shows an increaase in available space. Then when I rebooted, it detected an incomplete expansion. Log shows:

Tue Jan 31 08:48:07 2012 Volume expansion failed
Tue Jan 31 08:39:42 2012 System is up.
Tue Jan 31 08:39:25 2012 Incompleted file system expansion detected. Resuming...
Tue Jan 31 08:39:18 2012 Volume scan found no errors.
Tue Jan 31 07:55:59 2012 Please close this browser session and use RAIDar to reconnect to the device. System rebooting...
Mon Jan 30 21:33:32 2012 Volume expansion failed
Sun Jan 29 15:18:39 2012 Volume expansion or migration started. Do not interrupt the system during this time. When finished, email notification will be sent to the alert contact list.
Sun Jan 29 15:17:17 2012 New disk detected. If multiple disks have been added, they will be processed one at a time. Please do not remove any added disk(s) during this time. [Disk 5]

[mdgm]

What disks were installed when you last did a factory default?

Are you using single-redundancy or dual-redundancy. Is there another drive in the NAS along with your 5x3TB drives atm?

[jacw]

Gosh that was a while back I think I started out with 2x3TB plus 2x1TB and have never done a factory reset since buying the unit. Just before this recent additional drive, I have been running with 4x3TB drives seemingly with no issues. I recall having approximately 8.5TB of space at that point and I was approaching capacity with 8.1TB used. Now that I added the new drive, it shows an incremental amount of space but not a full ~2.8TB as it should. I have just rebooted with full checks so cannot access the unit to get exact details. I will do this and post when drive checks are complete but is it possible to get a partially succesful expansion that returns only a part of teh incremental capacity of the new drive?

[mdgm]

I think you might be hitting the limits of online expansion on EXT4 64-bit systems. Assuming you are using single-redundancy your volume capacity with 4x1TB would be more than 8TB less than the volume capacity with 5x3TB

[jacw]

Is that a limit on the Ultra 6? I have found people happily discussing sizes way in excess of 8TB eg. on viewtopic.php?f=24&t=51065

[mdgm]

16TB is the limit of what can be expanded to. I'm not talking about that. I'm talking about how much the volume can be expanded by online, which is 8TB.

[jacw]

Not sure I fully understand. So if I started with 2x2TB plus 2x1TB, I guess I lose 1 of the 2TB disks to redundancy so I have something less than 4TB to start with. You are saying I can only expand to 4+8 which is ~12TB (rather less given the self-serving way drive manufacturers have chosen to ignore the binary system) and so I am hitting that limit? Crud. That would mean I need to do a reset with consequent loss of data to gain the full capacity?

[mdgm]

Firstly the 4x1TB layer would've been created then expanding with a second layer using the remaining 1TB on the 2TB disks.

I would suggest contacting tech support (http://www.readynas.com/support) for advice.