Ready for expansion (RN Pro Pioneer Edition)-Seeking Advice

winger13 wrote:

1. Are you saying if I added only one 2TB (to empty slot #5), I only gain 1TB (over current capacity), and only if I add another 2TB (to empty slot #6) will I gain a full 2 TB of space? ... 2. Does adding a pair of 3TB's (into empty slots #5 and #6) yield only 2 TB of space, which is the SAME as adding a pair of 2TB's? If yes, why is this? I originally thought adding the pair of 3TB's yields a gain of 3 TB of space.

These are related questions.

When you have more than one disk size in the array, the xraid creates "layers" of separate raid arrays. Each RAID layer is separate (has its own independent RAID protection), and all are spanned by a single file system so as a user you don't see any of this complexity.

For example, say you have 2x1TB+4x3TB. installed. You have a 6x1 TB "base layer" across all drives (same size as the smallest drives). And a 4x2 TB "upper layer" across the 3 TB drives, which uses the extra space. Since you are using dual redundancy, both layers need to be RAID-6 - which needs 4 drives in the layer. You have that with these disks, so there is no problem.

If you were using single redundancy, you'd use RAID-5 in both layers.

if you have 4x1TB+2x3TB installed (step 1), you'd have a 6x1TB base and a 2x2TB upper layer. The upper layer only has 2 drives, so it isn't enough for raid-6 / dual redundancy. That is why step-1 only expands 2 TB, even if you add 2x4TB or even the new 2x6TB drive models. xraid2 won't/can't use the upper layer, because it doesn't have enough drives in it.

It would be able to use it for single-redundancy, and in this configuration xraid would use RAID-5 for the base layer, and RAID-1 for the upper layer.

If you were using flexraid instead, you set up the layers manually (with one volume for each). With flexraid you'd have the option to create a "c" volume with dual-redundancy (RAID-6) on the 1x6 TB base, and a "d" volume with single redundancy (RAID-1) on the upper layer. But XRAID2 won't do that. You can switch to flexraid, but you'd need to do a factory reset - rebuilding the NAS from scratch and reloading your data from backups.

winger13 wrote:
3. How dependable are 3TB's now? When I first purchased the NAS I read of many issues with drives larger than 1.5TB. This is the main reason I decided to start with 4x 1TB's.

First, you made the right choice back then. I didn't, and purchased many 1.5 TB seagates (USB and desktop). I wasn't using these in a NAS or RAID, and they began failing very quickly. One is still working, the others all died prematurely. I was fortunate not to lose data.

But this problem was solved in the second generation of 2 TB drives that followed. 3 TB drives have been out for a while, and in my experience are just as reliable as 1 TB or 2 TB models.

There isn't much data available to consumers that compares manufacturer reliability. There is an interesting article here: http://blog.backblaze.com/2014/01/21/wh ... uld-i-buy/

winger13 wrote:
4. Will there be a good chance SATA drives will not be found (at least at good prices) over the next four to six years time frame, replaced by Solid State drives? This is one concern as having SATA's either no longer being manufactured or sky-rocket in price because of limited supply will limit my future upgrade abilities.

SSDs are getting cheaper, and getting bigger. Crucial sells a 980 GB model with a street price of less than $500. It could be nice if they replaced hard drives, they are a lot faster. Though I think traditional disks in the larger sizes will remain available for a long time - smaller hard drive sizes on the other hand will be replaced by SSD much sooner. I have no crystal ball, but with current pricing that seems to be the likely outcome.

winger13 wrote:
5. Where are good vendors to search for good supply of approved (on HCL) drives? I tried Tiger Direct and Directron (two vendors I am familiar with) but cannot find any approved drives.

The bad news here is that Netgear is not updating the HCL as new drives become available. And they continue to deny support to people off the HCL. That creates a bad situation for us users. Most of the drives aren't available because they have been replaced with newer models. You can find the WD20EFRX and the WD30EFRX at both Tiger Direct and Directron.

I don't recommend using "green"consumer drives in the NAS. The WDC Red (and the seagate NAS line) are just as environmentally friendly, and are much better choices. After my bad Seagate experience I switched to Western Digital (though I know others have moved the other way because they had a bad run of WDC drives...). Personally I've never used enterprise drives, so I have no advice there.