Newbie - Parity drive concern question.

 

I am very interested to build my own UNRAID server but I have a stupid question due to my lack of knowledge  :

 

My understanding is all the information of all data is saved in only 1 parity drive. Therefore if you have 1 data drive failed, it still can be recovered by the help of the parity drive. My question is what if the parity drive is failed? Will I lost all/some of my data or there is some kind of data corruption? If it is the case, is there any way to always mirror the drive 1 (the parity drive).

 

Regards,

bondul

Losing the parity disk does not result in loss of any other data... except if you happen to have multiple disks failures, in which case the data on all the failed disks is also lost.

See http://lime-technology.com/forum/index.php?topic=2213 for a good discussion on the details.

 

Note, this is a much better situation to be in than other raid systems where multiple disk failures typical means loss of all data in the array not only the failed disks.

 

 

 

You may also find answers in the FAQ, particularly the first section, especially How does parity work?

Thank you very much for the answers 

So, I have to think as 1 and 0. it makes sense....

 

After I read further, It seems that the best way to configure unraid is to put the biggest drive you have as parity and put smaller drives as storage.

 

Also if I understanding it correctly: I will lost all the capacity on the parity drive since it is only being used as parity only. Is is hard to switch back and forth to make the drive as parity to storage and vise verse? Because, now I have one 1tb and on 1.5tb and some small drives. The only choice that I have is to use my 1.5tb as parity and the rest as storage.

 

Regards,

Bondul

After I read further, It seems that the best way to configure unraid is to put the biggest drive you have as parity and put smaller drives as storage.

 

Actually the parity drive must be equal or larger than the largest data drive. Its a requirement.

 

The best way to configure is to use the fastest drive possible for the parity drive once it meets the criteria above.

 

 

And you are correct about not being able to use the parity drive to save data. Once its set up there is no switching unless you do a backup and restore or add additional an additonal drive to replace the parity.

 

Set up the 1.5 as parity and don't look back. 

It's the coolest thing to just drop a drive in and magically the available space grows... well, it's not *that* simple, but it's not much more difficult than that.  You can always swap a larger drive for a smaller and it's just as easy.

 

If you're really worried about losing your 1.5 right now, set up your array with your 1T as parity and leave your 1.5T outside of your array.  Now the data won't be protected but it won't be any less reliable than if you put it directly in your PC.  And later once you've gotten enough on your array, move the 1.5T into the parity drive location and then add the 1T to the array.

 

To keep unraid simple - only change one drive at a time.  That way you never have the equivalent of a multi-drive failure.