Replacing Parity and upgrading drives.

[SavageAUS]

Hey all. 
I have just received 4 new drives for my server (all precleared already) and am currently doing a parity check before doing anything. 
To start out I have a 2tb single parity drive that I would like to upgrade to a 3tb drive and replace 2 1tb drives with 3tb drives and add an extra 3tb parity. 
my box can only hold 8 drives max so to do this I need to merge 2 of my existing drives onto a new 3tb drive. I know I need to upgrade the parity drive first, let it rebuild then I can swap drives in and out but I’m after a sanity check to see how I safely (not fast) merge 2 1tb drives onto a 3tb drive and add the extra parity drive. 
 

[SavageAUS]

So far I have upgraded my parity drive 2 -> 3tb, and replaced a 1tb drive with a 3tb drive. I guess my next step after letting this disk rebuild is to rsync the 1tb I want to remove to the new 3tb drive, stop the array, add new 2nd parity disk and start a new config? Then that leaves me with no spare spots to add new drives but a spare 3tb drive remaining, the other drives in my system are new (this year) wd red 2tb drives so I don’t really want to bench one just yet but I may swap it to the 3tb then use that 2tb in my camera system (currently 640G)
The 1tb drives I’m replacing are 5 year old blacks lol (5y, 8m, 12d, 5h) UDMA CRC error count 13. 
 

I am hoping from the views to this thread and no replies I am on the right track with what I am doing. 

[6of6]

I love that you're describing everything you're doing. My only caution, from what I've read, is why two (2) parity drives?

 

6.

[SavageAUS]

I could be wrong but doesn’t having 2 parity drives give the option for 2 drives to fail instead of one? 

[6of6]

Having 2 parity drives complicates things more than most people need...

 

My first plan was 2 parity drives, but then I realized... parity isn't a backup and I can use those extra drives for backup!

 

Two things is better than one with parity. Parity only keeps important things *working* if there's a (drive) failure.

 

I hope this helps... and, most of all,  please post your endeavors to the end.

 

6.

[SavageAUS]

Well if there is no benefit to adding an extra parity drive I’d rather use the drive to add additional storage. Still waiting for rebuild to finish.


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[SavageAUS]

Still an hour and a half on the rebuild to go and still weighing up my options on if I add a second parity or increase array size.
If I have dual parity I have 6 array disks and single parity will give me 7 array disks.
Now that all my hard drives are new and wd reds I should be able to semi trust them and if I ever go to a bigger case I can add a second parity drive then but I can also add it now and be “future ready” hmmm decisions.


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[JorgeB]

2nd parity is IMHO a small price to pay for the added redundancy, especially for larger arrays, but like mentioned it's not a backup, first make sure you have backups of anything important, also for six array disks single parity should be OK in most cases.

[SavageAUS]

Oh absolutely raid is not a backup I am well aware. If I stick with single parity it will be an array of 7 disks but with dual parity it would an array of 6 disks. Does this make much difference? Prior to the upgrade I was only using ~60% space now that usage is down to 52% with the upgrade from a 1 to a 3tb drive. I don’t see my storage needs growing too much too soon so I think dual parity now would be best for me. I can always upgrade the remaining 2tb to 3tb drives down the line if storage becomes a concern.
Now to safely rsync the 1tb black to the new 3tb red. Or is unbalance plug-in the “best” way?


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[SavageAUS]

I used unbalance to rsync the data over then stopped the array and removed the drive. I then added the new 3tb drive into my server and applied a new config assigning dual parity drives. No data loss. Now to replace an existing 2tb drive with the last 3tb drive to grain the extra 1tb of space and use the 2tb in my home camera system.