Want space and speed-RAID? and if so, which?

[doc4x5]

I'm not quite sure where to put this but thought Mac Pro users are the most likely to use or consider a RAID.

The four 8 TB drives in my Thunderbay IV (Thunderbolt 2) are getting close to full. It’s attached to my 2013 Mac Pro (64GB OWC RAM, 1TB SSD).
In the Thunderbay IV, I have a “Photos” drive, two backups of it and a backup of my SSD. All backups are done each night with Carbon Copy Cloner. I have other off-site backups of the photos and the boot SSD.
I have some older drives purchased as I gradually worked myself up to the 8's. I like to have all my photos in one place, with multiple backups of course.

Would a RAID (eg 3 6TB drives using RAID 5 [Soft Raid] giving a 12TB capacity be faster than a single drive or should I bite the bullet and get some larger drives, eg 10 or 12 TB?
At this point I’d prefer to do whatever will be faster for Photoshop saves. I’ve done a bit of web searching and it is not clear to me whether RAID 5, or any RAID configuration, would be significantly faster than a single disk for PS saves. I could get a new Thunderbay 4 (Thunderbolt 3) with Soft Raid and keep all my backups in the boxes even if I used one of the Thunderbays for the RAID. This would be forwardly compatible with whatever my next computer would be (iMac 2019, or new modular Mac Pro if it’s affordable).

My other option, as I spend endless hours thinking this through, is just a plain RAID 0, I know this provides no protection against disk failure, but my current system doesn't either. Should my "Photos" disk fail, I'd be left with my backups the oldest of which would be from last night. A RAID 0 should be faster than my current system which writes my Photoshop files to the "Photos" disk. I do not earn money with my photos, I'm an avid amateur, a retired bum who puts almost as much energy into my photo passion as I did to my previous profession. The loss of even a full day's work would be frustrating but not tragic.

 

[Mikael H]

With RAID, it works pretty much like this:
RAID 5 will only cost you the equivalent of 1 drive in space ”lost” to parity data. Large sequential reads will be performed across stripes and should feel nice and fast compared to a single drive. However, small random writes will be taxed: Each write operation results in a Read(data)-Read(parity)-Write(data)-Write(parity) operation against the underlying disks.

RAID 10 will cost you the equivalent of half your drives ”lost” as mirror data. As with RAID 5, large sequential reads will be performed across stripes and will feel fast compared to a single drive. The big benefit compared to RAID 5, is that each write operation only results in two I/O operations: Write(data)-Write(mirrorData).

I personally strongly prefer RAID 10 in most cases if I can choose, for anything other than specific loads with low concurrency and high read-to-write ratio. It costs a bit more in disk space, but it frees me from thinking about how I want to use the disks. But if you mainly use a disk solution for pure storage, then RAID 5 may be a good choice. You could use your system drive for your daily photo work, to keep things fast, and only move finished photos to the RAID array.

But yes, of course: If you truly only want speed and size, and if you’re confident in your backups, then I agree that RAID 0 can be an acceptable choice.

 

[barmann]

I'm not sure what kind of workflow you are talking about .
Are you editing a certain amount of images a day, or just processing lots of image files ?

Either way, Photoshop mostly benefits from having a fast scratch disk(s) dedicated to editing and processing, or you can use the fastest disk and assign it to that task assuming enough space is available .
Might be an issue in the tcMP unless your internal disk has lots of unused space left .

The disk(s) with your work files on it benefit your workflow if they are fairly fast, and will open and write the PS files more quickly when saving, but editing is all about scratch disk performance in PS ( as drives are concerned ) .

As for backups, Raid is not really a backup solution .
If you value your files, and work, just run a a backup program to clone your work files to a seperate external drive now and again ; or do a manual backup frequently .

I always use a couple of extrenal drives during important editing to copy my work files to as often as it makes sense ; with USB 3 or TB time is not an issue .