Computerworld - Network-attached storage (NAS), once only available (and affordable) for enterprises, is becoming more common for small business and even home use. And necessary -- if you are looking for secure backups for your data, a single backup disk collecting data once or twice a day is no longer enough.
I looked at three NAS units that recently appeared on the market and that could suit the ambitious home or small business: Synology's DS409slim; Seagate's BlackArmor 440; and Netgear ReadyNAS NVX. None are enterprise level, but each fits a particular spot in a networking environment. They range in price from around $750 all the way up to $2,000.
For the tests, I used a desktop system powered by an AMD Phenom 9600 quad-core processor running at 3GHz with 2GB RAM and a 500GB Western Digital Caviar Blue with 16MB cache. I used a Linksys SD2008 network switch to connect the devices.
The tests were run with a 4,661-item (8.05GB) data package consisting of a mixture of files and folders containing data, pictures, videos and music. They were first transferred from a local hard drive in a Windows 7 RC computer to the NAS device. The package was deleted from the source computer and then transferred from the NAS unit back to the computer's hard drive. A simple copy and paste was used for both operations; times were recorded manually using a Tag Heuer digital stopwatch.
Keep in mind that network traffic as well as the specifications of the hard drives used in a NAS unit will affect overall performance. Typically, the former is out of your control. That's why you usually schedule backups for after-hours in general.
In addition, the drives that you use will affect performance as well. Out of the three NAS units reviewed here, only Synology's lets you purchase the drives separately. Otherwise, you're pretty much locked into whatever drives the manufacturer believes works best with its product.
Why? Because RAID 6 uses dual parity to provide data security. Whereas RAID 5's single-parity technique will allow you to rebuild your data should a drive fail, RAID 6 will let you rebuild your data should a drive fail during a rebuild of your data. The cost for that additional peace of mind is that more disk capacity will be used for parity information and write times will be slower than they are in RAID 5. As a result, in order to give the tested NAS units a chance to put their best feet forward, I opted to test using RAID 5.
In the real world, how likely are you to encounter that type of double failure? If you keep an eye on the Self-Monitoring, Analysis, and Reporting Technology (S.M.A.R.T.) data provided by these units' management tools at least once per month, you'll probably know well in advance of most hardware failures.
Of course, there's always the potential for catastrophic failure or for failures in areas that S.M.A.R.T. doesn't monitor. Still, in my opinion, your odds of experiencing a drive failure during a data reconstruction is probably the same as those should a meteor strike a region of the planet that is experiencing a tsunami at the same time.
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