No I'm not shifting the goal posts, you did by suggesting that RADIZ groups be used and forgot to mention that there are minimum requirements in order to make that work.
The problem you referred to, from the outset, occurs with many drives.
There are very well known issues with ZFS and RAIDZ performance and that overcoming them isn't trivial because it requires specific configurations to get around them with. RAIDZ just isn't suitable for small disk configurations, such as those most people here will use.
For someone claiming very well known issues with ZFS and RAIDZ performance
, why did you forget to mention that this RAIDZ performance problem is one of IOPS, not bandwidth? In the case of large files and sequential reads or writes, RAIDZ parallelizes available bandwidth very well. I do not consider Raw/DNG or working PSD/TIFFs for most photographers to be small files. JPEGs might be, it depends.
Do you suppose scaling out IOPS is important for a photographer?
Do you likewise disqualify RAID 5? If not, why not?
What's the advantage of this enclosure over sticking disks inside the desktop computer, which would invariably provide better striping performance? By a lot. And would be cheaper.
Also, the specs are confusing: Is it 15TB, 10TB, or 6TB capacity? Is this built-in or host RAID?
Thus eSATA is perfect because it is the speed of the local disk except to something external.
Whether it's perfect or not depends on the other hardware in the workflow, which we either don't know, or I missed it even though I went back and looked. I think on the one hand this enclosure is overkill on the quantity of storage, but it's bottlenecked by interface. I would consider a different approach, but again it depends on other hardware.
DAS is for performance, it's for hot files. NAS is for availability, it's for cold files.
Hot files are: scratch space, preview/cache files, work-in-progress PSDs and TIFFs.
Cold files are: those pixels that haven't been touched in a month, let alone today.
It really does not make sense spending extra money on fast large DAS for cold files. At least not until we have more reliable file systems that can be both resilient and fast, by pooling (aggregating) those disks together.
So I would bias the budget for DAS to be small, but as fast as practical for the size I need for daily work: hot files.
And I'd bias the budget for NAS to be large, not as fast, but higher availability, for the cold files. Plus I get SMART and UPS monitoring built-in, a more reliable file system, and automated replication features (to either an on-site or off-site duplicate NAS or cloud storage).
I could even have a "sweep" script that moves all fast DAS files to the NAS once or twice a day. And then after 7 days of aging, deletes them off the NAS. This, in case I "forget" to move my hot files to more reliable storage.
Similarly, eSATA is going to be quicker for them to access than any NAS (Network Attached Storage) that's connected to Gigabit ethernet (3Gb/s > 1Gb/s).
GigE NAS comes close to single local disk performance, ~ 90MB/s is reasonable to expect although I've seen them push 110MB/s.