nars

"Parity is already valid." option auto starts check CORRECT

15 posts in this topic

While doing some tests... at some point I just wanted to start a new config and used "Parity is already valid." option, after reassigning all hdd's on the right slots... as I knew it was already valid... though I did noticed that it automatically starts a 'CORRECT' parity check, is this by design?

 

If I'm telling it that I know parity is valid wouldn't it make more sense it starts a 'NOCORRECT' check just to let me know if parity is REALLY valid (or just don't do automatic parity check at all) when using that "Parity is already valid." option? let's suppose I did swapped parity hdd by mistake when re-assigning hdd's, then I suppose the 'CORRECT' parity check would just auto start destroying data on the hdd wrongly assigned as parity? :(

 

I know that usually the recommended procedure on forum after a new config is to suggest just start array with no parity hdd assigned, to make sure all hdd's are on the right places, only then assign parity hdd... surely a good procedure... but that way "Parity is already valid." option can't just be used as it really only shows when we have a new config.

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You can CANCEL the check ... and then start a non-correcting one if you want.

 

If you know it's already valid, however, there's no real reason not to do a correcting check.

 

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You can CANCEL the check ... and then start a non-correcting one if you want.

Sure, but it may be too late then :)

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You can CANCEL the check ... and then start a non-correcting one if you want.

Sure, but it may be too late then :)

 

Too late for what??    If you used the Parity is Valid option, you should KNOW that it's really valid.  So on reboot you can simply cancel the automatic parity check ... and then, if you want, run a non-correcting check.    If you were wrong, of course, and parity wasn't valid, then the correcting check would have already "corrected" a bunch of "errors" => but if that's the case, you should either let it go ahead and finish (so you'll have good parity);  or simply unassign/reassign the parity drive and run a full parity sync (doing the full correcting check would do the same thing -- it would just report "sync errors" for all the bits that needed changing).

 

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You can CANCEL the check ... and then start a non-correcting one if you want.

Sure, but it may be too late then :)

 

Too late for what??    If you used the Parity is Valid option, you should KNOW that it's really valid.  So on reboot you can simply cancel the automatic parity check ... and then, if you want, run a non-correcting check.    If you were wrong, of course, and parity wasn't valid, then the correcting check would have already "corrected" a bunch of "errors" => but if that's the case, you should either let it go ahead and finish (so you'll have good parity);  or simply unassign/reassign the parity drive and run a full parity sync (doing the full correcting check would do the same thing -- it would just report "sync errors" for all the bits that needed changing).

I meant for example in the case you by mistake assign a data disk to parity slot or just start it with a missing hdd (say you made hardware changes and the hdd is just not there)... i.e. you use the option and something is wrong... If a check NOCORRECT would be done you would see errors and say to yourself "hey, something not ok here... let's check it..." while with check CORRECT you would say "hey, something not ok here... oh damn... it already started writing parity to the wrong hdd or wrong parity, with a drive missing, etc".

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Agree -- if you assign a data disk as parity AND still do a "Parity is Valid" you' definitely cause problems (and lose data).    HOWEVER, the "Parity is Valid" option should absolutely NOT be used unless you're CERTAIN you have everything assigned correctly and that parity IS indeed valid  :)

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Agree -- if you assign a data disk as parity AND still do a "Parity is Valid" you' definitely cause problems (and lose data).    HOWEVER, the "Parity is Valid" option should absolutely NOT be used unless you're CERTAIN you have everything assigned correctly and that parity IS indeed valid  :)

While I agree I still think control should be in the users hands not the software where parity checks are concerned.  I would even rather it come up from a hard shutdown and NOT do a parity check instantly.  A simple warning that parity is invalid and array is unprotected until a "sync" is performed message can be displayed next to the start button instead of instantly begining a parity check.
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Yes I've noticed that a "trust parity" operation fires up a parity-check.  This is not the intent.  I intended that if you Start the array with "Parity is already valid" box checked, that no parity check is automatically started.  This has been fixed in 5.0.

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Just to add a very small note, not a big issue, but the "Parity is already valid." checkbox is visible and we are able to use it even if we don't assign a parity disk, what is obviously no sense, and if we use it that way then unraid seems to get confused thinking that there is actually parity protection available (parity check options available, etc)... and also if we later want to add a parity disk then it also get's some strange behavior (want's to clear "new" disk's, despite it seems to do nothing) and seems impossible to add it. Anyway it's no sense that someone would  tick it that way for sure... :)

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Can confirm that on rc16b no parity check is auto started when using "Parity is already valid." option. Thanks Tom :)

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UGH It looks like this has reverted again in 6.1.2

I Init'ed an array, Trusted the Parity, Started it in maintenance mode, and the system started up with a correcting parity check writing 7303 changes to parity before I could cancel it :/

 

I realize this is an old thread, but the fact that it said it was fixed twice made me think it would be safe.

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In fact I think it was never fully fixed, or it got back again long time ago yet on last 5.x builds... it was mostly fixed... but I did also see it happening again sometimes... but I couldn't reproduce it when I wanted, that's why I did never posted about it... I guess it must happen depending of something that I don't know what it is... maybe when we do array changes... or... not sure really :(

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