New Guy here with a few questions on the headwear.

[Grumpy1040]

I’m going to use this server for Media, Torrents for the Library, System Backups, Cad file storage, Doc storage, and VMs,  and I may play some games.

My current Hardware is from my x99 system.

Mother board is an ASUS x99 PRO USB 3-1

CPU i7-5930K Water Cooled

32 GB DDR4

Main GPU Nvidia RTX 3060 12GB

Secondary GPU Nvidia GTX 1660 Ti 6GB

My first question is about the Parity drives, I have heard it said that 6 or less drives require 1 parity drive, more than 6 require 2. Is that 6 total including the parity ? I have a Total of 7 WD Red 4TB drives.

My second question is how much Cache is really needed? Currently I have at my disposal are 2x Nvme drives at 2 TB each, in the mother board PCIE slots, 2x 1TB SSDs, and 1x 2TB SSD.

Just keep in mind that we have 10 SATA6G ports, and I was wanting to use one of them for a Blu-Ray drive to copy DVDs and Blu-Rays.

Thanks for any answers.

[ConnerVT]

There is no requirement to how many, if any, Parity drives are needed in the array.  You can have none, one or two.  The only real requirement for the Parity drive(s) is that it must be larger than any of the data drives in the array.

 

If you have 1 Parity drive, you can recover from one drive failing in the array.  If you have 2 Parity drives, you can recover from two drives failing.  (And as I know someone will chime in shortly - Parity is not a replacement for backing up your data.)

 

The 6 more/less recommendation (the number varies depending on who you ask) is just a threshold of when you may consider a 2nd parity drive.  The more drives in your system, the more likely that 2 drives may have an issue.  But it makes little sense to have 2 parity drives if only a few data drives, as that makes a larger % of total drive space not available for data.

 

As for Cache,  again there is no actual requirement.  The original role for the Cache was to be a faster buffer for writes to the array, as the array is generally slower (due to calculating/writing parity).  Data sits in the buffer (where it is accessible) and later moved to the array at a scheduled time.  So if you do use cache, it should be able to hold the largest file you would write to the array.  each defined Share in your system can specify if/how Cache is used.  In my system, I do not use cache for my Backup or Media, as they sometimes see very large file sizes and I am in no rush to copy (automated tasks).  Those I write straight to the array.

 

Many folks use their cache for other things, such as storing their Dockers' Appdata.  In a lot of systems, that cache drive is the only SSD so it is faster access for Docker applications.  The recent versions of Unraid allow for multiple cache (now called "Pools"), and these pools can contain multiple drives with some basic RAID modes if desired.

 

So, as you see, you have options.  It all depends on what you want the server to do.