Hypothetical question.

 

My largest data drive is 3TB. So are my parity drives.

 

If I switch out one of the parities for a 5TB device and it later kicks the bucket, can I replace that 5TB parity with a 3TB drive? Or will unraid complain about using a smaller disk (even though it is no smaller than the largest data drive)?

 

Thanks

 

PS. The reason I'm asking is because I would like to start upping the size of my drives slowly. But I can't afford to buy 3 5TB drives at once just to replace two parities and have a spare. I also don't want to replace just one and not have a spare for it. I currently do have a 3TB spare.

I haven't tested it but I would expect it to be fine because, unlike a data disk, a parity disk doesn't contain a file system.

 

It would absolutely work fine, although I'm not sure which of the following two scenarios you'd have to use:

 

(1)  You could simply switch to another (smaller, but still >= largest data drive) parity drive and Start the array -- then just wait while it rebuilt parity.

 

(2)  If by chance UnRAID didn't recognize this special case and balked because the drive was smaller than the one you were replacing, you'd simply do a New Config (with the option to keep all the assignments);  assign the new drive as parity instead of the old (failed) drive; and then Start the array -- and just wait while it does a parity sync.

 

Total time wouldn't be more then 2-3 minutes different between the two alternatives => basically you'd just try #1; and if it complained when you hit Start, you'd just take a minute to do the New Config, then Start the array.

 

 

 

 

It would absolutely work fine, although I'm not sure which of the following two scenarios you'd have to use:

 

(1)  You could simply switch to another (smaller, but still >= largest data drive) parity drive and Start the array -- then just wait while it rebuilt parity.

 

(2)  If by chance UnRAID didn't recognize this special case and balked because the drive was smaller than the one you were replacing, you'd simply do a New Config (with the option to keep all the assignments);  assign the new drive as parity instead of the old (failed) drive; and then Start the array -- and just wait while it does a parity sync.

 

Total time wouldn't be more then 2-3 minutes different between the two alternatives => basically you'd just try #1; and if it complained when you hit Start, you'd just take a minute to do the New Config, then Start the array.

 

Thanks for the detailed answer.

 

A follow up question. . . With the first option, while rebuilding, if a data drive goes belly up, I should be fine since I would have the one parity drive, but with the second option of doing a new config, if a data drive dies during that process, I would lose the data on that drive, is that right?

I'm almost sure you wouldn't need to do a new config, but you could still be protected if you did, when doing the new config assign all the data disks and the good parity, start array with the trust parity option, stop, assign the other parity and start to begin sync.

...

A follow up question. . . With the first option, while rebuilding, if a data drive goes belly up, I should be fine since I would have the one parity drive, but with the second option of doing a new config, if a data drive dies during that process, I would lose the data on that drive, is that right?

 

First, I'm fairly sure #1 will work => BUT I don't think which approach you're using matters if a data drive goes belly up during the rebuild.

 

BECAUSE -- your premise in this question is that your parity drive has failed.  ["... If I switch out one of the parities for a 5TB device and it later kicks the bucket ..."]    So you'd already be running without a valid parity drive.

 

UNLESS you're talking about a dual parity system  (which I guess you are since you said "one of the parities").    In that case, then you definitely want to use #1.  Hopefully it works with a smaller drive => but if not, I wouldn't do the New Config ... I'd simply bite the bullet and buy another parity drive of the same size.

 

 

I'm almost sure you wouldn't need to do a new config, but you could still be protected if you did, when doing the new config assign all the data disks and the good parity, start array with the trust parity option, stop, assign the other parity and start to begin sync.

 

This would do the trick nicely in a dual parity situation.  Assuming that the "parity is already valid" option would work okay with only one parity drive installed.  It seems like it should, however, as long as you (a) be sure to assign the "good" parity to the same parity slot it had been in;  and (b) ensure that the disk assignments are in the same slots they'd been in (not hard to do, but important that you do it).

 

Johnnie => Have you by chance tested this?  [i.e. a New Config with "parity is already valid" on an array that was dual parity but you're only assigning one parity in the new config -- especially only the 2nd parity drive)

 

Johnnie => Have you by chance tested this?  [i.e. a New Config with "parity is already valid" on an array that was dual parity but you're only assigning one parity in the new config -- especially only the 2nd parity drive)

 

Yes, and it works, but in this it wouldn't be necessary to do a new config.