I just noticed this NAS on Amazon - http://www.amazon.co.uk/gp/product/B...A3P5ROKL5A1OLE which might be on offer today (7th January) for under £150. I've no idea whether it would satisfy a requirement for backup storage, but it may. The software manual is quite interesting - http://www.downloads.netgear.com/fil..._23Dec2015.pdf
Around pages 23-24 there are details of the various RAID modes, and perhaps Netgear specific modes. In the X-RAID mode the total storage capacity assuming similar drives, is one less than the total number of drives - so effectively with this 2 drive unit, the total capacity available with 2 installed drives is equivalent to a single drive without RAID protection. Other RAID modes may give different trade offs between protection levels and available capacity.
Page 24 elaborates further. RAID 1 provides protection if one disk fails. RAID 5 provides protection if one disk fails, but requires a NAS with at least 4 drive bays - so the 2 drive unit here wouldn't work with RAID 5. RAID 6 provides protection if two disks fail, but also requires a NAS with at least 4 drive bays. RAID 50 requires a unit with at least 6 drives, and the total capacity available is 2 less than the number of drives installed. RAID 60 also requires a unit with at least 6 drives, but the total capacity available is 4 less than the number of drives installed. Thus for RAID 60 with a 10 drive unit [maybe a 12 drive unit, with 10 drives installed], the effective capacity would be 60%. A 12 drive unit populated with 10 x 1 Tbyte drives would have an effective capacity of 6 Tbytes in RAID 60 mode. 10 x 1 Tbyte drives would cost about £500 - http://www.amazon.co.uk/Red-3-5-inch...words=ReadyNAS
I didn't realise before looking at the manual that the drives are formatted according to a RAID/NAS specific (Netgear?) format - which makes sense if you think that there has to be some infrastructure to support the RAID architecture. I'm not quite clear if the drive formatting would work with drives formatted for other manufacturer's RAID NAS systems.
The particular NAS noted (2 drive unit) does not appear to have any wireless connections. I am not in fact sure if any NAS systems have this, so to use with mobile devices another network router or wireless access point would be needed on the networks. Most ethernet LAN networks will contain a wireless router nowadays, so that is probably not an issue.
Does RAID operation reduce risk significantly? I don't know. The protection offered is against total data loss if one drive fails, or with more complex systems, two drives can fail. How likely is that, and how much does the risk reduce? A 12 bay NAS unit can cost more than £2000 and go up to £5-6000 - see http://www.dabs.com/search?q=ReadyNAS Drives to populate a large RAID NAS unit could also cost up to £1000 or even more.
4 bay NAS devices seem to be around £2-400, while 6 bay ones seem to start around £600. The prices often don't include the cost of the drives, either. Some businesses could find RAID operation useful, but for domestic use the costs are probably too high to justify the possible levels of protection. Besides data protection, there might also be a performance improvement, though how significant that would be I can't say.
Obviously all this extra "protection" could be rendered useless if someone drops a brick on the NAS unit, or it is stolen, or is damaged by fire or water. Which other manufacturers supply RAID systems which might work within a domestic network? Possibly such systems are pointless for domestic use because of cost, and also taking into account likely (or unlikely) failures. The first step is surely to quantify the value of the data - either "real", or "how much is it worth to you?", and also the degree of risk before embarking on a potentially very expensive storage solution for risks which may be avoidable in other ways.
Around pages 23-24 there are details of the various RAID modes, and perhaps Netgear specific modes. In the X-RAID mode the total storage capacity assuming similar drives, is one less than the total number of drives - so effectively with this 2 drive unit, the total capacity available with 2 installed drives is equivalent to a single drive without RAID protection. Other RAID modes may give different trade offs between protection levels and available capacity.
Page 24 elaborates further. RAID 1 provides protection if one disk fails. RAID 5 provides protection if one disk fails, but requires a NAS with at least 4 drive bays - so the 2 drive unit here wouldn't work with RAID 5. RAID 6 provides protection if two disks fail, but also requires a NAS with at least 4 drive bays. RAID 50 requires a unit with at least 6 drives, and the total capacity available is 2 less than the number of drives installed. RAID 60 also requires a unit with at least 6 drives, but the total capacity available is 4 less than the number of drives installed. Thus for RAID 60 with a 10 drive unit [maybe a 12 drive unit, with 10 drives installed], the effective capacity would be 60%. A 12 drive unit populated with 10 x 1 Tbyte drives would have an effective capacity of 6 Tbytes in RAID 60 mode. 10 x 1 Tbyte drives would cost about £500 - http://www.amazon.co.uk/Red-3-5-inch...words=ReadyNAS
I didn't realise before looking at the manual that the drives are formatted according to a RAID/NAS specific (Netgear?) format - which makes sense if you think that there has to be some infrastructure to support the RAID architecture. I'm not quite clear if the drive formatting would work with drives formatted for other manufacturer's RAID NAS systems.
The particular NAS noted (2 drive unit) does not appear to have any wireless connections. I am not in fact sure if any NAS systems have this, so to use with mobile devices another network router or wireless access point would be needed on the networks. Most ethernet LAN networks will contain a wireless router nowadays, so that is probably not an issue.
Does RAID operation reduce risk significantly? I don't know. The protection offered is against total data loss if one drive fails, or with more complex systems, two drives can fail. How likely is that, and how much does the risk reduce? A 12 bay NAS unit can cost more than £2000 and go up to £5-6000 - see http://www.dabs.com/search?q=ReadyNAS Drives to populate a large RAID NAS unit could also cost up to £1000 or even more.
4 bay NAS devices seem to be around £2-400, while 6 bay ones seem to start around £600. The prices often don't include the cost of the drives, either. Some businesses could find RAID operation useful, but for domestic use the costs are probably too high to justify the possible levels of protection. Besides data protection, there might also be a performance improvement, though how significant that would be I can't say.
Obviously all this extra "protection" could be rendered useless if someone drops a brick on the NAS unit, or it is stolen, or is damaged by fire or water. Which other manufacturers supply RAID systems which might work within a domestic network? Possibly such systems are pointless for domestic use because of cost, and also taking into account likely (or unlikely) failures. The first step is surely to quantify the value of the data - either "real", or "how much is it worth to you?", and also the degree of risk before embarking on a potentially very expensive storage solution for risks which may be avoidable in other ways.
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