Greetings,

 

I'm about to upgrade my parity to a 4Tb WD RED. I've recently replaced a dying parity drive and upgraded in the past, but I haven't actually thought too much about the protection side of things while I'm doing it.

 

Is my thinking correct that the array loses protection during the parity upgrade?

 

Yes sir.  While you are replacing the parity drive, there is no protection while it syncs.  If you lose a drive during that time you have a problem.  But...you would still have the OLD parity drive, so maybe that would be some protection if you were to put that drive back in.  Some of the smart fellers can comment on that.

Yes and No.

 

Yes, you lose parity protection while the new parity sync is being done.

 

But No, that doesn't necessarily mean you are running "at risk" => as long as you do NOT use the array during the parity sync; and do NOT do anything with the old parity drive.

 

If something went awry (i.e. a data disk failed) during the parity sync, you could then:

 

(a) replace the old parity disk;  and then

 

(b) do a "New Config" (on the Utils tab) -- assigning all of the same data drives and the OLD parity drive -- and checking the "Trust Parity" box ... which would tell UnRAID the parity drive was valid.

 

You could then replace the failed drive and let the new one rebuild;  and THEN do your parity upgrade.

 

So there we go.  You have some protection as long as you don't mess with that old parity drive.

So there we go.  You have some protection as long as you don't mess with that old parity drive.

...and do not write to the unRAID until parity is safely restored.

Good call. 

 

Amazing piece of software if you think about it.  I have lost 2 data drives over the last few years and have never lost any data at all (knocks on wood).

Thx very muchly for the input.

 

Gary - when you say to NOT use the array - do you mean NOT write to it - or does this also mean not to watch anything off it as well?

 

I usually don't do anything when I'm making changes, but it's tough being unable to watch something off it - especially as we rarely watch anything else like Live TV.

 

It's also quite a long process on my system - approx 22 hours for a parity check / rebuild. Not sure how much the time will go up stepping up to a 4Tb drive. Then there is the parity check straight after.

 

I also worry a lot about the power going out as we seem to have that a lot as well. My UPS only lasts about 30 mins. Thankfully I wasn't doing the upgrade yesterday, as we suffered a 6.2 earthquake not far from us. Power was glitching a lot. I wasn't much fun

 

Appreciate the help.

You're correct -- it's okay to READ from the array ... as long as there are no writes.

 

If you're just streaming a file, that's fine.  But remember that some programs may do writes as part of that process (e.g. Plex if it's doing some transcoding).

 

But if, for example, you're simply playing a DVD stored in a Video_TS folder (or as an ISO), then you're fine.    The key is that there must not be ANY writes, or you'll invalidate the parity on the old drive.