Regarding parity drives and existing volume sizes

[kode54]

I am currently running with 2x 4TB drives and 1x 640GB, my oldest surviving drive. I had a 1.5TB drive die last year.

 

Anyway, I was wondering if I should plan ahead for future capacity and buy a 6TB or larger drive for parity. Would this make sense if I am not currently using parity and none of my drives are nearly that large? I only ask this because of the size discrepancies I've experienced with the WD Red NAS 4TB drives, having bought one, then bought another identical model almost a year later only to find that it has about 100MB less capacity.

[itimpi]

This can be a good idea, but without knowing your expected future plans it is difficult to be sure.  Also you do not mention how many spare drive slots you have to give an idea what expansion you can do within a 4TB limit.  One has to bear in mind that drive prices tend to drop over time so if you do not need to buy an additional drive for some time then it may not be worth rushing things.

[garycase]

... having bought one, then bought another identical model almost a year later only to find that it has about 100MB less capacity.

 

??  Was one of these extracted from an external drive?  I've NEVER seen a size discrepancy in WD Reds -- 3TB, 4TB, 6TB, or 8TB in over 50 of them I've purchased in the last few years.

 

Sometimes an external drive will have a slightly different setup than the drives sold for internal use.    Another possibility is that somehow one of your drives has an HPA on it that was created by a system it was installed on ... although this is much less likely with newer systems than it was a few years ago.

 

[garycase]

... as for your question =>  Yes, if you're going to add a parity drive to your system it's a good idea to make it as large as whatever drives you'd like to buy for your data drives, so you don't have to upgrade the parity when you start buying the additional drives.

 

[kode54]

??  Was one of these extracted from an external drive?

 

Ah, yes, the slightly larger one was extracted from a WD MyCloud that went on the fritz, and I didn't feel like having it serviced only to lose all the data I had stored on it.

 

I have two SSDs and room for one more data drive on my current license, but may expand my license later if I ever get a machine with the capacity for a lot of drives. (I have one more Intel controller port left, and two from the added vendor my board threw in.)