Parity update frequency for specific share

[drumstyk1]

I apologize if this is a silly question. I am planning to use my unraid to backup mainly movies/tvshows but I am also a photographer and would like to store important wedding photos on there. I will be using a cache drive but is there a way to get unraid to immediately do the parity check of just a specific share (photos) when I transfer to it? Obviously my other media is less critical and i would rather it check the parity less frequently to save power and avoid the hdd spinups. i realize that my movies would then be unprotected until the monthly check but I think i can live with that to save a few bucks.

[JonathanM]

Parity is constantly maintained, there is no need to check after a transfer. The reason monthly parity checks are recommended is for verification that a single drive failure could be rebuilt. The problem with relying on parity without the check, is that many times a drive can silently fail, and until that portion is called on to be read, you will never know. A mostly empty drive is still required to be FULLY read to reconstruct a drive failure, so if you have a failure on a well used drive, a second failure on a drive you almost never use will cause the loss of both drives.

 

A monthly parity check fully exercises all drives so you can detect problems early before you lose two drives, and can't rebuild.

[lionelhutz]

Your question isn't really correct. The parity is updated when the data is moved from the cache drive to the array disks. However, I'd recommend you set the pictures share to not use the cache so they get copied right to the protected disks. You can also set the mover to work more often than once a day, however that can cause slowdowns to the point the cache disk is useless if the mover is running while you're copying items to the cache.

[drumstyk1]

Ah, i see. I was confused on my terminology. I thought that when you transferred to the array, the entire parity had to be redone but it seems it can just append for the new data. I went ahead and set my photos to bypass the cache drive and I am going to try to setup this monthly parity check. Thank you both for the help!