I wasn't trying to nitpick ... I just think it helpful for the user to know all the relevant implications of the storage technology. Said technology can be complicated. But for example, comparing a RAID 5 implementation with a single big disk I'd expect:
- Better read performance from the RAID 5
- Worse write performance from the RAID 5
- Access to your data even if a disk fails .... though until the disk is replaced and reconstructed there are issues.
As I mentioned, it's great that one still has access to the data when a disk fails, but disk reconstruction can really use up a lot of disk bandwidth, so it might be hard to do much during that step, and of course there is the possibility of a double disk failure. But while the RAID 5 won't help you on data input when you copy the photos off the cards onto the computer, the write once/read many usage pattern of photo processing is a nice match for RAID 5's read speeds.
Another example, compare a RAID 5 using HDDS with a single fast SSD:
- I'd expect the SSD to smoke the RAID 5 on writes, and probably be a lot faster on reads, depending on the type of SSD
- If the SSD fails, then no access to data until the backup drive (which is probably not another fast SSD) is copied to a new SSD. During that time, you are vulnerable to a double disk failure (backup drive failing). Which is why I have a cloud backup and a local backup.
I haven't played with home use NAS setups. As others have pointed out, you need a really fast network for a NAS to compete with local attached storage in terms of throughput and latency (and good software implementations). That said, the use of networked storage is quite common in the business world, even in performance critical applications, though they use very fast networks.
Right now I have one relatively slow SSD with my latest photos on it, and one HDD with older photos, both backed up to a 5400 RPM drive. And a cloud backup. I'm thinking about getting a bigger faster SSD and putting all the photos on it. My restore time would be slow, but daily use very fast for a modest cost. But I'm happy with the SSD speed for normal operations.
If lightroom was more NAS friendly I'd have a high speed NAS so that I could easily access the photos imported into LR from multiple computers. But LR is not NAS friendly and I don't want to try and hack up a solution to make that work.