QNAP TS-459U-RP Turbo NAS Reviewhardnrg - July 22, 2010
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So far in the review, I have explained most of the features in detail, with some examples of how the features can be used. On this final page of the Testing section, I would like to illustrate a few of these features in detail, to demonstrate how you can achieve various tasks on the TS-459U-RP.
Online RAID Capacity Expansion
The TS-459U-RP has the ability to expand the storage capacity of an existing RAID array by switching the disks out, one-by-one, for higher capacity hard drives. In this example, the NAS has been populated with a 2x160 GB RAID-1 array. When the array has completed its initial build, you then have the option to Expand Capacity.
At the Expand Capacity screen, you can click on Change to replace one of the hard drives with a larger one. You are prompted to remove the existing hard drive. There is no need to power down the NAS, and you can continue to access the data on the array.
When you insert the new larger disk, the NAS automatically initialises it, and begins rebuilding the array.
At this point, there is the same ~150 GB RAID-1 disk volume, but now using one 160 GB and one 1.5 TB disk.
You have to replace the hard drives one at a time, so the next step is to repeat the disk swap procedure for the second hard drive in the RAID-1 array. The result at this stage is the same ~150 GB RAID-1 disk volume, but now on two 1.5 TB disks. You should note that, in this state, the disk volume is only using 11% of the capacity of the hard drives.
On returning to the Expand Capacity screen, the button below the hard drive listing, "Expand Capacity", is now enabled. Clicking this button expands the size of the disk volume to fill the full capacity of the new hard drives, in this case 150 GB to 1397 GB.
This expansion procedure takes several hours, but does not require a backup procedure, and is faster than the alternative of backing up to another storage device, creating a new disk array, and restoring the backup.
While the RAID-1 array synchronised, I went ahead and installed two more 1.5 TB disks for the next demonstration.
Online RAID Level Migration
If you started with a RAID-1 array, and need yet more storage space, you can achieve this by migrating the array to another RAID level. In RAID Management, you can click through to the Migrate section, wherein you can see the free drives available for migration.
Selecting a drive and a new RAID level gives you an indication of the prospective new capacity. Clicking on Migrate reminds you that the hard disk used for migration will have any residing data destroyed.
Once the migration is well under way, you can see an approximation of the remaining time for the procedure. There is nothing left to do except check back later to see the new RAID-5 array.
If you wanted to expand a RAID-5 array from three disks to four, you would choose the Add Hard Drive option in RAID Management.
At this point, you may not want to use the fourth hard drive, and keep it as a spare in the event of a failure of one of the disks in the RAID-5 array. Instead of leaving the disk sitting there doing nothing, you can configure it as a hot spare, which the NAS would automatically use to rebuild a degraded array.
A hot spare is one way of having a fail-safe on top of the one-disk redundancy of RAID-5. You could also opt to migrate the RAID-5 array to RAID-6, gaining two-disk redundancy. You wouldn't gain any additional capacity, but it's nice to see that RAID-6 is available as a disk configuration, so users with very important data can have extra assurance of storage integrity.
Again, the lengthy migration procedure takes several hours; you can still use the disk volume, and after a while it will become a RAID-6 array.
RAID-5 Data Protection
I simulated a disk failure by removing one of the hard drives in a four-disk RAID-5 array. The NAS quickly recognises the incomplete array, and operates in degraded mode, relying on the XOR calculations to maintain operation.
On inserting a new or used disk, the array will automatically be rebuilt. Rebuilding a RAID-5 array is one of the longest procedures the NAS can undertake, and took just less than 10 hours for the four 1.5 TB disks used in this review.
Finally, the rebuild operation is complete, and the RAID-5 array returns to its original state.
Apple Time Machine Support
QNAP provides the NetBak Replicator software for making backups from a Windows PC, but what about backups on a Mac? Well, you can use the built-in Time Machine feature of Mac OSX 10.5 or later to make automated backups to the TS-459U-RP. With Time Machine support enabled on the NAS, you can select and log in to it from the Mac machine.
Time Machine automatically schedule the first backup, and initialised the allocated Time Machine space on the NAS.
The backup process was very much a sit-back-and-wait procedure, and OSX would automatically handle future backups, replacing older backups with new ones when the available Time Machine disk space allocation on the NAS runs out.