Just kind of a general question.  Can I use my unRaid array with XBMC while running a Parity check?

Yes.

 

Yes, it might be a bit slower.

Yes, but you may get studdering or other problems with playback. I do. I've never worried to much why or tried anything to fix it because I just scheduled the parity check to happen in the middle of the night so it wouldn't interfere with playback.

 

I've never worried to much why or tried anything to fix it ...

 

The "why" is simple => you're significantly thrashing the disk that your playback is coming from -- it's head is "bouncing back and forth" between the next sector it needs to read for the parity check and the next sector it needs to read for the playback.

 

While you CAN use the array during a parity check, it's simply a good idea not to.  Like you, I do all my parity checks at times when the system isn't going to be otherwise used.  it WILL work, but it's going to be much slower at BOTH the activity you want to do AND the parity check during the time it's trying to do both.    If you're trying to do something that's relatively low-bandwidth (e.g. playing music) you probably won't notice it; but for high-bandwidth activities (e.g. movies) you can easily notice the effects.

 

 

OK, I will expand on my answer for Gary.

 

In my answer replace "why" with "why studdering occurs on my system when lots of other people can playback movies just fine while a parity check is occurring".

 

Does that make my answer more clear? I certainly don't need the drive seeking explained to me like a 2 year old.

 

Most likely, I could do some kind of tuning of the system to fix it but I really don't care enough to bother spending the time.

 

Didn't mean to upset you with the explanation -- you indicated you'd never bothered to figure out why it was happening ... and I simply noted the reason.

 

As I noted, whether or not you'll see issues from the seeks depends on the bandwidth of the material being accessed => if you're listening to music, you'll likely not notice any issue; with SD movies it can probably stream fine as well, as long as the disk buffers are large enough to hold what you need between seeks;  with HD or BluRay material, its far more likely you'll see issues.

 

You can, of course, adjust the disk "tunables" to somewhat alter the balance between parity sync and read priorities ... this may help somewhat; but as you've already noted (and I agree) it's best to simply run your parity checks when you don't otherwise need the system.  [Personally, I do NOTHING on the system during parity checks -- no reads; no writes; no media streaming; etc.]