Upgrade parity drive?

[starcat]

Guys,

 

I am about to upgrade from 4TB to 8TB parity drive and was thinking in order not to loose parity while upgrading, to assign the new precleared 8TB drive as a 2nd parity drive and after everything is done to remove the 1st (old) parity drive (and re-assign it as a regular data drive). Would this work (going then back from 2 to 1 parity drive) and do I need to take care about anything special?

 

I am currently running 6.2.0-rc3 with a Pro license.

I am going to use an 8TB Seagate ST8000DM002 as my new parity drive and later also for data drives.

 

Thanks very much in advance.

[JorgeB]

It's not a problem, be aware that with Q parity there will be some "limitations" compared to using P only, you cant re-order disk slots an maintain parity and performance could be a little slower during parity checks (though probably there will be no difference with your hardware).

[starcat]

Ok, thanks! I just want do add the new parity and then as soon as done, remove the old parity drive and going back to 1 parity drive. So those limitations shouldn't hurt actually.

 

If I just remove the old parity and start a new parity drive calculation, I will be running unprotected during the rebuild period. I hope to avoid this while using the 2nd parity drive feature.

[JorgeB]

If you change parity2 to parity1 you'll need to do a new sync, parity won't be valid.

[starcat]

Oh.. which means being again unprotected. Can't an array stop and clean detach of the second parity disk be done?

[JorgeB]

Parity2 can be "cleanly detached", the problem is that the parity information is calculated differently than parity1, so they are not interchangeable.

 

If you can avoid any writes to the array during the upgrade you can use the old parity if anything goes wrong.

[starcat]

If you can avoid any writes to the array during the upgrade you can use the old parity if anything goes wrong.

 

Thanks, that's good to know.

[Lantesh]

Out of curiosity why don't you leave the old parity drive in place?  Add your new 8TB drive in the parity 2 slot, and leave parity 1 alone for now.  If you don't need any additional added capacity immediately you are better off leaving it in place.  Then when you can afford to buy another drive for the parity 1 slot you can then recycle the old drive, and add it to the array.

[garycase]

Ok, thanks! I just want do add the new parity and then as soon as done, remove the old parity drive and going back to 1 parity drive.

 

If you just want a single parity system, there's no reason to do it that way.  I understand your concern ...

 

... If I just remove the old parity and start a new parity drive calculation, I will be running unprotected during the rebuild period.

 

... but that's not really a problem.  Just do the following:

 

(a)  Do a parity check to be certain all is well -- assuming you have no drive errors or sync errors, you're ready to upgrade.

 

(b)  Just remove the old parity drive and set it aside; replace it with the new 8TB drive; and then let the system rebuild parity.  DO NOT use the array during this rebuild.  While technically you're running "at risk" during this operation; you're not really risking anything as long as you don't change the data on the array (e.g. don't use it during the rebuild).    If anything goes wrong, simply stop  replace the old parity drive; and do a New Config with the "parity is already valid" box checked ... and you're right back where you started, so you can easily recover.  (e.g. rebuild a failed drive; etc.)  You're never really "running at risk", since you always have the original, valid, parity disk ready to use if needed.

 

Odds are very good nothing will go wrong and you won't have the hassle of restricting the configuring back to single parity.

 

 

[starcat]

Thanks guys, highly appreciated!