Hey all, I am looking at buying an unRaid device to store backup files we generate daily. I am not sure if this is the right place to ask but I was looking at the unRaid cache pools and I was wondering if the cache pool is smaller than a single file being copied, what happens?

Hey all, I am looking at buying an unRaid device to store backup files we generate daily. I am not sure if this is the right place to ask but I was looking at the unRaid cache pools and I was wondering if the cache pool is smaller than a single file being copied, what happens?

It is written directly to the array, bypassing the cache.

Excellent, thanks for the quick answer. I have a follow up if you don't mind, just to make sure.

 

If the cache becomes full, for any reason, it will bypass it?

Does it immediately trigger the "mover"?

Does the "mover" run on a schedule or is it intelligent with resource usage?

Excellent, thanks for the quick answer. I have a follow up if you don't mind, just to make sure.

 

If the cache becomes full, for any reason, it will bypass it?

Does it immediately trigger the "mover"?

Does the "mover" run on a schedule or is it intelligent with resource usage?

 

If the cache becomes full, and you attempt to write to a cache enabled share, it will bypass the cache and write directly to the array.  If OTOH, you are attempting to write DIRECTLY to the cache, it will fail with a disk full error.

 

To the best of my knowledge, no it does not immediately trigger the mover when the cache is full.

 

The mover runs daily at 3:40 am.  This is the default schedule, and can be changed if you wish.  You can also set it to run hourly, weekly, or monthly.

At one point, I thought you needed to set the minimum free space on the cache drive to be larger than the largest file you foresaw copying, because it would fail mid-copy when the file size exceeded the remaining space.... Any further writes would then bypass the cache drive...

 

Is this still the case (or am I completely mis-remembering...)?

Hey all, I am looking at buying an unRaid device to store backup files we generate daily. I am not sure if this is the right place to ask but I was looking at the unRaid cache pools and I was wondering if the cache pool is smaller than a single file being copied, what happens?

 

I'm intrigued by what files you're thinking of copying that might be bigger than your cache pool. 

I was thinking of buying small SSDs (250GB) for the cache pool. 4 of them if that configuration works because they are like $60 each now. One of my backups alone is a 900GB file. It is an Art department share that gets tarred and compressed lightly for performance issues. The entire backup process currently takes almost 24 hours for a single pass per day for about 40 offices. Most of the issues are performance of disks, I currently run Drobo 5Ns as offline storage and it is terrible for performance but it has been outgrown to be fair.