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ReadyNAS NV+ v1 volume C offline after expanding
My ReadyNAS NV+ v1 was nearing volume capacity so I purchased two new WD Red 2TB drives (for slots 3 and 4). Removed old 1TB drives and replaced (see log notes below). After volume resync and expani...
Interesting, I had no idea RAID4 was being used. I had a NV+ V2. Never tried Vertical expantion on it. Then again I havn't tried it on my 516 either. But it looks like you really waste a lot of HDD space until you have enough drives. It's ot has bad with a 6 drive unit as it is with a 4 drive unit, but looks like to really get any real space gains, you need to swap out 3 drives, 1 at a time. Rebuild, a second, Rebuid, and then a 3rd and rebuild.
RAID4 over RAID5 seems like a strange choice to me. Not sure why Netgear would use it? Seems RAID 5 is faster is READ/WRITE over RAID4.?!?!
http://www.24hourdata.com/blog/which-better-raid-4-or-5
https://en.wikipedia.org/wiki/Standard_RAID_levels
JBDragon1 wrote:
Interesting, I had no idea RAID4 was being used. I had a NV+ V2...
Only the sparc-based NAS used RAID-4. Everything newer (including the 4.2.x x86 NAS) use software RAID-5. That includes your NV+ v2 and your 516.
RAID-4 can be a write bottleneck, since all the partity blocks are on the same disk. Plus the disk usage is uneven - the partity disk does a lot more i/o.
The RAID-4 decision predates Netgear and goes back to Infrant (they built a custom sparc chip for the NAS back in 2005). That chip had a built-in RAID controller, and my guess is that the hardware architecture dictated RAID-4.
Also, the sparc NAS require all the disks to be the same size (a common restriction when Infrant was founded).
JBDragon1 wrote:
Never tried Vertical expantion on it ... But it looks like you really waste a lot of HDD space until you have enough drives.
Well with XRAID/single redundancy you do need to install two larger drives to avoid wasting space. The capacity rule (as you likely know) is "sum the disks and subtract the largest". You can't do better than that with single redundancy.
The cheapest way to expand (cost per TB gained) is to get a NAS with enough slots that you can have some empty bays. You can also opportunistically go with larger drives as old ones fail also.
Even though vertical expansion isn't the cheapest way to expand, it still is cheaper than buying another NAS.
Learn something new every day. I like it! It makes more sense now. As for expantion. Using Netgears drive Calculator, it was interesting looking at the results for a 4 bay to a 6 bay NAS and going with Vertical expantion once the slots are all filled, which they are now on mine with 6 3TB HDD. I still have 2.42TB free, but I have so many Blu-Ray's that are not on it yet. I'm also updating many of my 480P movies to1080P, sometimes 720P just to save some space.
But playing with the Calculator, even throwing in 2 6TB HDD's, you think you would get 6TB of new space, but it's only like 2TB. It's a lot of waste really until to get to a 3rd HDD and better as you add more. If it's only a 4 drive NAS, You're better off buying 4 new HDD at once, and swapping in one at a time, rebuild, add another, and so on. Otherwise it's really a lot of wasted space. It's cheaper then buying another NAS, of course. Of course you end up with 4 smaller drives and nothing to do with them? Even if I kept my old NAS and popped in the old 3TB HDD's, it wouldn't be large enough to backup my newer NAS with the larger HDD. I need buy another 8TB HDD to backup on as it is. That old NAS wouldn't have worked with these 8TB drives.
I have to say, that NV+ V2 was very poky. Network speed was really SSLLLOOWWWWW. The 516 is 4-5 times faster over my Gigabit Network. I can only imagine how slow the older Sparc one is in everything. How is going the EDA-500 expantion route? Is Netgear still supporting that? I've heard some pro's and con's in that area. It's also pretty pricy for was is basically a HDD case with a ESATA controller.
Hi JBDragon1,
As far as I know it is still being supported.
Regards,
BluRays do take a lot of space. FWIW you can save a surprising amount by removing audio tracks you don't need.
JBDragon1 wrote:
...even throwing in 2 6TB HDD's, you think you would get 6TB of new space, but it's only like 2TB.
6x3TB -> 4x3TB+2x6TB expands the volume from 15 TB to 18 TB. In TiB units that's ~13.6 TiB -> ~16.3 TiB. After that you will gain 3 TB per drive.
The starting point (6x3TB) forms one RAID-5 layer. The disk upgrades create a second protected RAID-1 layer (2x3TB each). If you don't do that you can't maintain single redundancy protection. The two RAID layers are joined by the system into a single volume.
When you upgrade a third drive, that new layer is converted to 3x3TB RAID-5.
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