Wednesday, April 29, 2009

QNAP: Add another drive to RAID 6?

Yesterday I mentioned that everything was working well in terms of building a 7x2TB configuration while the remaining 2TB of data from an external connection was transferred over to the RAID.

Well, this morning all the copying seemed to have finished overnight which meant it was time to plug the last 2TB drive and expand the size of the RAID.

Funny, I was about to say "RAID array" but that is redundant being as RAID does mean "redundant array of individual disks" so saying it would have been like referring to a "redundant array of individual disks ARRAY". No, duh.

It looks to be there is a terminology difference in the jargon used and its confusing. What makes it more difficult is that there isn't enough specific information about what one has to do if using RAID 5 vs RAID 6. After much head-to-knuckle banging (at the possible data loss in one fell swoop of a misconfigured array), a clue on the Wikipedia definition of RAID 6 helped. So it looks to be that its considered by some "RAID 5 + 2 spare disks". Meaning that I could take the "Add hard drive" under the RAID Management tab even if it says only for RAID 5 and implement it on my RAID 6 - which I did. The results are in the first graphic above as well as some intermittent dual-beeping coming from the TS-809 right now.

Those 2 beeps (per the manual, yes of course I read it) mean any of the following things: HDD volume is filling up (don't think so), HDD is indeed full (nope), HDD is in degraded/failed mode (nah), HDD starts/currently rebuidling (YES!!).

So, right now the RAID is rebuilding as a result of the added disk and also calling the expand module. Its still stuck at 1% but like the initial building where I was letting it multi-task copying from the last 2TB drive in the set, its more probably a result of me copying 69-GB of data at 18 MB/s over the gigabit network to one of the NAS' shared drives.

Time to wait and see and a post-update later ....


  1. Did this end up working? We've hit the same wall.

  2. Yes! However I'm still not completely sold on RAID6 and with the features of ext4 being possible, thinking to redo everything. See the following entry ->

  3. Not to ressurect an old post, but this post is high when googling "qnap add disk to raid".

    RAID 6 is RAID 5 with an extra parity. You can loose a total of 2 disks from the array before loosing data. You could also think of it as a RAID 5 with a hot spare that is 'pre' rebuilt.