Bob Andersson wrote:
My very personal take on this is that RAID 6 is too much of a good thing and that RAID 5 is good enough for a home NAS box. It's pretty unlikely that you'll lose a second hard drive before you have a chance to replace a failed drive and let the NAS rebuild the array and it still doesn't make sense for any NAS to be the only backup solution deployed, particularly for critical data.
I don't know whether you already know about this or not but according to the calculations in this article
the simultaneous failure of two drives in RAID-5 should perhaps not be your main concern.
My personal opinion is that most private users don't really have a use for RAID-5. Even for daily backups you can use an external USB/eSATA drive. The nice thing about current modern external drives is that they spin down after being idle for a while which most likely will prolong their lifespan. It'll also remain in such a suspended state if you would shut down the computer and leave the USB drive under power. It would only spin up for the daily backup and shortly after that's done it'll go to sleep again.
I currently have four external Western Digital 1TB drives and two systems with 640GB (also WD) RAID-1 arrays. Such a mirrored size gives me plenty of time to collect a considerable amount of data that is not absolutely safe but as a result of the mirroring has a high degree of protection against data loss. I'm very careful about malware of course although most malware is not out to destroy your data anymore. When I fill up the 640GB array I move the data to one of the external drives which are switched off 95+% of the time. I use few operating hours for these external drives as part of my strategy against data loss. For most situations in private use you can do without storage outside your computer that's on-line 24/7/365. Saves on electricity too. In a professional environment demands can be very different of course.
When I bought the last two 1TB drives I consciously chose for 2x1TB over 1x2TB because 1TB is still pretty huge (well over 200 DVDs) and IF a drive would fail you won't lose 2TB of data in the worst case scenario but only 1TB.
I copy my photos (eventually) to both RAID-1 systems and have them on an external drive AND have also copied them to the netbook I bought a few months ago (250GB HD). Six copies should be enough.
I only delete photos from my memory cards when the photos on it are at least on one extra drive besides the RAID-1 array of my main computer.
On a side note security wise. I've recently installed Prey
laptop tracker software on my netbook which helps to find your property if it would ever get lost/stolen. It does a nice job and if you don't yet have it or something similar installed you should definitely take a look at it. The site could do with a little more information but you'll most likely figure it out.
When in doubt..... Press the shutter.