[solved] unRAID, parity, and what drives should I use?

[htpc1602]

Hi all, loving the trial so far - learning a lot and having a good time doing it. Apologize for any incorrect terminology in my post.

 

In my current HTPC, I have a 120GB SSD for Windows, three 3TB WD Reds (two 95% full, one 70% full), and one 4TB WD Red (25% full). These Reds are all media drives, no backups, no RAID - spooky. I just picked up some 8TB Easystores, so that adds to my available space, but I'm not apposed to selling the smaller Reds if they aren't necessary anymore.

 

My question is about what I should do with my current drives. I have ~9TB of media currently, and a total of 29TB of raw storage. What is a good setup to start, keeping in mind I have the following:

3x 3TB 

1x 4TB
2x 8TB

 

Also, I definitely skipped past a lot of the talk about parity like a dummy, as I wrongly assumed I could just add parity drives and it would just put my data on it like a 1for1 backup like RAID1. So, knowing that is wrong now and reading through some of the wiki, is there a simple man's explanation for how a parity or two parity drives work in the unRAID system?

 

Thanks.

Edited July 19, 2018 by htpc1602

[trurl]

30 minutes ago, htpc1602 said:

is there a simple man's explanation for how a parity or two parity drives work in the unRAID system?

 

Did you see this wiki?

 

https://lime-technology.com/wiki/UnRAID_6/Overview#Parity-Protected_Array

 

2 parity is similar, just a different calculation across the disks.

[htpc1602]

That "dumbs" it down for me quite well, thank you.

 

So regardless of the size of the disks in the array, as long as I have a parity disk that is as big as the largest disk (8TB in my case), I should have a low chance of losing any data? I understand a data drive and the parity drive can fail before I realize and I should also have another backup, but as long as I have a parity drive, I should worry less about data loss?

 

And 2 parity isn't a duplicate of the same drive, but instead a different calculation to protect from multiple simultaneous drive failures?

Edited July 18, 2018 by htpc1602

[JonathanM]

11 minutes ago, htpc1602 said:

I should have a low chance of losing any data?

Parity + the rest of your data drives can rebuild a drive, but it doesn't replace a true backup.

 

Drive failure is only one way to lose data. Accidental or malicious deletion or corruption are much more common ways to lose data, and parity does nothing to protect from those causes.

 

If you care about your data, it must be backed up, which means a second copy somewhere besides your main machine.

17 minutes ago, htpc1602 said:

And 2 parity isn't a duplicate of the same drive, but instead a different calculation to protect from multiple simultaneous drive failures?

Correct. Parity by itself doesn't have any sensible data, it's only usable in concert with all the rest of the drives.

[trurl]

15 hours ago, htpc1602 said:

I understand a data drive and the parity drive can fail before I realize

 

Be sure to setup Notifications so unRAID can notify you when you begin to get a problem with a disk.

[htpc1602]

I will definitely do this when I set up my machine after my trial expires. I have two 8TB drives on their way, and I'll be buying a Define R5 some time next month.