(SOLVED) Advantages of larger parity hdd than array hdd?

[Rimrom]

Hi, since I really don't know where to look for that answer, I am just going to ask it here:

 

Is there any advantages in having larger size hdd for parity versus same size parity/array's hdd ?

Let's say I have an array of 8 hdd of 4Tb, if my parity is a 14TB hdd rather than a 4Tb hdd, is it going to tolerate the lost of 2x 4tb or 3x 4tb HDDs ?

 

Thank you

Edited November 28, 2020 by Rimrom

[Squid]

Nope.  Only a single drive.

[itimpi]

The only reason to have parity drives larger than any data drive is to give you the option to later add/rebuild data drives of up to that size.    If you are not going to do that then having a larger parity drive is a waste as the extra space is not being used and parity checks take longer to complete.

[Rimrom]

Thank you !

[ainuke]

Consider how many bays/SATA ports you have and what kind of upgrade path you want. If you have ports/bays for days, it won't matter as much if you only ever use 4TB drives. But if you only have, say 6 SATA ports and want to reserve two for parity, then you're limited to 4 ports for storage drives (assuming you don't have any used for optical drives or whatever). While 16TB (4x 4TB) may seem like a lot right now, as cameras take larger file photos, and you upgrade your movies from 1080p to 4K (or 8K someday), the available space shrinks quickly. Using a larger parity drive NOW, enables you to expand those 4 drives as they die to larger sizes, giving you more space out of the same 4 ports/bays.

My experience with having a home server over the years is that it's not nearly on the same upgrade schedule as my gaming computer, so keeping the existing hardware (mobo, cpu, ram, etc) means keeping as much headroom in the storage array as possible. Sure, PCI cards can be used to expand the number of SATA ports available, and one can upgrade the parity drive at any point. So it's not like you're locked into what you choose now. But using a 6 or 8 TB drive right now for parity will enable all subsequent drives that you're either adding or replacing to be 6 or 8TB, respectively.

Edited November 15, 2020 by ainuke
forgot to add last word for clarification

[trurl]

I have always had a small case and like it that way. All my capacity increases have been replacement with larger drives. I currently have 8TB parity with 6TB data disks so I am ready for my next replacement when needed. And the older smaller disks find other uses as backups or other builds for friends, etc.

 

And as I often say each additional disk is an additional point of failure.