Lost file

[efrhm]

Hello all,

I've just noticed there is an excel file missing from my protected array (Ver. 6.1.2).

I can only find the ~$****.xslx useless file 

Background: In the last couple of months I've suffered from occasional parity drive failures which I've validated to be due to a poor power power cable.

Can this be the reason? Hence, is parity build doesn't always perfect?

I'm quite worried that my array isn't safe as I imagined, especially because I've noticed in the past several problems while trying to play, evidently corrupted, media files (which were OK).

thanks,

Haim

 

[trurl]

Parity drive doesn't contain any of your data. Any particular file is completely on a single data drive. Most likely explanation for the missing file is deleted by user. A much less likely possibility would be filesystem corruption. Parity will not help in either case.

 

Do you have another copy of the file somewhere? A single copy of an important file, even if it is stored on a fault-tolerant system such as unRAID, is never a good idea.

 

Do you have any idea which specific disk the file should be on? Which user share?

[Helmonder]

Hello all,

I've just noticed there is an excel file missing from my protected array (Ver. 6.1.2).

I can only find the ~$****.xslx useless file 

Background: In the last couple of months I've suffered from occasional parity drive failures which I've validated to be due to a poor power power cable.

Can this be the reason? Hence, is parity build doesn't always perfect?

I'm quite worried that my array isn't safe as I imagined, especially because I've noticed in the past several problems while trying to play, evidently corrupted, media files (which were OK).

thanks,

Haim

 

Parity in unraid is used to make sure you do not loose data when a disk fails... It does litteraly nothing for filesystem corruption or user error, even more bluntly: lets say there is some kind of corruption, then either the parity will just make sure it can re-create this exact corruption should the disk fail, OR it will not notice the corruption, if you then run a parity check the system will again make sure that parity is consistent with the physical disks.

 

So: parity makes sure you get back what you had before a disk failed. It does not do anything wrt file corruption , or user error..  This is what backups are for..

[efrhm]

Hermonder and trurl - that's exactly what I know.

Since I didn't deleted the file (maybe my children have done it accidentally, though not likely...), maybe a plausible explanation is a PC Windows crash while the file was opened, or something like that.

Unfortunately, I don't have copy of the file.

Another question, probably 1st grade one:

Say I have a parity error as an outcome of a periodic parity check. What to assume: data disc error or parity disc error?

Thanks

[Helmonder]

If the file is gone it is gone... Unraid does not make backups so your file is most probably lost.. You could try some tricks on the filesystem to recover stuff, alas I am no expert in that..

 

As far as the second question: If parity finds an error it means that the parity drive is not consistent with the complete set of data drives. It can be either situation. Even if you would -know- that the error is not on the parity disk, then there is no way of knowing on which disk the error exists.. This is why in the event of a parity error, parity is always corrected on the parity disk. The system continuously tries to make sure that it can recreate a disk in its current state (untill a moment of redball).

 

It has been rumoured that version 6.2 of unraid will bring a 2nd parity disk, this will help with double disk fail, but it may also be able to pinpoint -which- disk is not conforming to parity.. At that point you could fathom a situation where you could choose to make the disk situation conform to parity, at this point in time it is not possible to "correct the disk instead of the parity disk", since the system does not know what disk to correct..

[efrhm]

Understood. Thanks you all good guys for clearing this issue. I'll certainly have to make backups of important files.