Hello everyone! 

 

For years I've used two 8tb external hdds connected to a spare laptop running Linux as a "nas." My storage has almost run out, so I bit the bullet and purchased hardware to build an actual nas. I plan to install unraid onto it.

 

Currently I have 8 10tb hdds coming in the mail, I will set 2 parity drives and the rest array.

 

The guide I followed did not mention anything about a cache drive, I had no idea about this until I began reading more about unraid.

 

A reddit post says this 

 

Write speed to the array is slower than max gb seeds due to calculations etc. 

 

Many use a cache as the landing zone for incoming data, it writes to the cache for a cache enabled share then nightly (or on schedule) the data moves from the cache to the array.

 

So this means that if I include a cache drive, all data is written on the cache. My issue is that I want to transfer my 14tb of data to the nas when I set it up. Does this mean i can only transfer whatever size the cache drive is and then wait for unraid to move it to the array?

 

Also, every thing I read about the cache drive people say to use an ssd. I have a spare 2tb sata mechanical drive. How much would that impact my transfer speeds if I used that compared to an ssd?

 

Thank you all

If you need to write more than cache can hold, don't cache. Each user share has settings that control how (or if) it uses cache. 

 

You can do the initial data load before you add parity, then it will write at the speed of the disk being written. 

 

HDD as cache would be faster than writing to parity array, but SSD would be better. Cache or another pool is also used to improve performance of Dockers/VMs.

Buy a M.2 (this is NVMe) to PCIe adapter, mirror two cheap NVMe drives, and make a pool. It's fantastic. When the pool (of NVMe drives) is full it will dump to your slower disks. 

 

Quote

 Does this mean i can only transfer whatever size the cache drive is and then wait for unraid to move it to the array?

Yup. You can disable cache on a per share basis and go direct. When doing an initial copy I rsync directly to a disk inside of the array using the Linux console.  

 

If you are going to run 12 drives I'd use a SAS HBA. If you are using SATA drives don't use an expander. This is pro level option, but the best and cheap. 

Thanks guys for the reply. I grabbed a 2th nvme for cache. Just waiting on my mobo to come in the mail then I can begin building 😬

Edited January 11, 20251 yr by Valr