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RN104 added 2 disks to raid 1 system. Don't know what it's doing
I had 2 disks in it as Raid 1. I tried to read search the community for what would happen if I added another pair of disks. Frankly, I found it entirely confusing (should there not be a manual for ...
When you go to the third disk, it converts the volume to RAID-5.
That gives you protection from a single disk failure. Total capacity is the sum of the disks minus the largest.
For instance, if you started with 2x4TB and now have 4x4TB, the volume grows from 4 TB to 12 TB. The NAS reports the 12 TB in TiB (1 TiB = 1024*1024*1024*1024 bytes), so it will show 10.9.
When you go to the third disk, it converts the volume to RAID-5.
That gives you protection from a single disk failure. Total capacity is the sum of the disks minus the largest.
For instance, if you started with 2x4TB and now have 4x4TB, the volume grows from 4 TB to 12 TB. The NAS reports the 12 TB in TiB (1 TiB = 1024*1024*1024*1024 bytes), so it will show 10.9.
So, if I undertand you correctly, given I had 2x 2TB disks (in a raid 1), and I added 2x 4TB disks the new thing will look like one big 2+2+4=8GB volume?
So, is there a document that I missed that explains what the result will be if you add or replace disks given a particular starting configuration?
Thanks
adiamond2 wrote:
So, if I undertand you correctly, given I had 2x 2TB disks (in a raid 1), and I added 2x 4TB disks the new thing will look like one big 2+2+4=8GB volume?
Well 8 TB, but otherwise correct.
When you replace disks, you can either replace them with one that's the same size, or replace them with one that's at least as large as the biggest disk already installed.
Similarly, when you fill an empty slot, you need to add a disk that's at least as large as the biggest disk installed.
There is an XRAID calculator here: http://rdconfigurator.netgear.com/raid/index.html However, it doesn't clearly state the two constraints above. FWIW, there are other constraints with OS 4.2 and OS 5 ReadyNAS.
Chapter 2 of the ReadyNAS OS 6.6 Software Manual discusses volume configuration. The "Software Manual" can be downloaded from the ReadyNAS OS 6 User Guides and Documentation page.
re:Chapter 2 of the ReadyNAS OS 6.6 Software Manual discusses volume configuration. The "Software Manual" can be downloaded from the ReadyNAS OS 6 User Guides and Documentation page.
I looked at it before. Yes, it kind of discusses volumes but, unless I'm missing it, what it doesn't do is say is what it will do if you (e.g. me) add disks to an existing setup.
coloatty wrote:
Chapter 2 of the ReadyNAS OS 6.6 Software Manual discusses volume configuration.
Well, sort of. It describes what horizontal and vertical expansion are, and says specifically that adding the first disk won't add space. The capacity information is there but tacitly assumes that all disks are the same size. It is silent on the underlying RAID modes that are used with XRAID (likely assuming that will confuse most users).
Most importantly, it doesn't give any information on the disk sizes that need to be used for replacement or expansion.
-It seems to say that if you have 2x4TB installed, that you can horizontally expand by adding a 2 TB drive, which won't work at all.
-if you have 2TB+2x4TB, the manual seems to say that you can replace the 2 TB drive with a 3 TB model and get vertical expansion. However, that won't work - the system can't expand, and will waste the space.
-Many people assume that the array can be shrunk if the space isn't all used - which can't be done. The manual doesn't speak to that (either way).
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