We're running an NV+ that has been serving well with a pair of 500MB drives in XRAID config. We've been having to archive a lot lately since we've been pretty full on it so in the past few days we've added two new 2T drives. Each has now been successfully through initialization and expansion - BUT the total capacity of the NV+ is shown now as just 1363 GB.
How do we get access to all of the capacity that should be available in XRAID with these four drives (in theory, 2.5T minus the normal stuff).
X-RAID on your NV+ (v1) uses the capacity of the smallest disk. X-RAID is a RAID-4 array. In this case the 2x500GB + 2x2TB is treated as 4x500GB. So 1500GB before overheads, measurement discrepancy etc. Now remember disk manufacturers consider 1KB = 1000 Bytes i.e. 1GB = 1000^3 Bytes whereas the NAS considers 1KB = 1024 Bytes i.e. 1GB = 1024^3 Bytes. So 1500 / 1024^3 * 1000^3 = 1397GB. When you allow for overheads etc. you'll get that 1363GB figure.
Removing two drives from your volume would leave it dead. To go to two disks you would need to backup your data and do a factory default (wipes all data, settings, everything).
With two 2TB disks you would have more space than you have now.
What version of RAIDiator are you running? If not already running 4.1.7 or later I would update to that (be sure to verify update completed successfully) before doing the factory default.
If you want to simply expand your existing volume you would need two more 2TB disks and to add one 2TB disk at a time (wait for resync to complete etc. before replacing the next disk).
Should have answered your question above. It's 4x500 - 1x500 = 3x500 = 1500. There is the redundancy overhead of the capacity of one disk. If any one disk fails data remains intact. RAID is not a replacement for backups however. If you primarily store important data on the ReadyNAS please backup that data regularly. See Preventing Catastrophic Data Loss
Thanks for the reminder, but we do indeed use a hard offsite backup and archive of this data on a regular basis. That's one of the reasons that the smaller configuration has served us effectively to now. The RAID itself is just a primary line of defense against the inevitable disk failure - a good one at that.
