Getting the Correct setup

Actually, SoftRAID works great with SSD and HDD's in a RAID 1+0.

All reads are done on the SSD's, so you get the speed. It is cost effective and while HDD's are slower, they have a more predictable lifecycle.

2 Other Scenarios:

1. 360G SSD & 3 HDD 1.5T
a. Do I set it up with a 1+0, or
b. will RAID 4 or 5 work

2. Using the rest of the 3 HDD
a. RAID 4, Does the indexed drive need less space?
b. Is three drives ok for RaID 4 or 5?

1. This is not an ideal setup, use your original idea, as you should have 2 SSd's. An excellent RAID 1+0 configuration is 2 SSD's, and 2HDD's, where the HDD's can be the "backups" to the SSDs. Do not use "old" drives, I suspect you might be cobbling this together with older 1.5TB drives.

RAID 1+0 is the safest RAID for your data. With 2 SSD drives, it will give very good performance also.

2. All partitions in a RAID volume are the same size. You can create a RAID 4 or 5 volume with 3 drives, yes.

With your drives, do this:
1. 360GB SSD - boot volume (non RAID)
2. 500GB SSD + 2 2TB HDD - main data volume
3. 500GB Mirror (HDD) - backup system volume
4. 1 TB Mirror volume - scratch/backups, etc.

I'm looking to put together a FAST software RAID array using a T2 or maybe T3 enclosure (If available soon) using 4 Samsung new EVO850 SSD's (2x1TB, 2x 500GB). My questions:
A. What is the best configuration for speed? My use would be for photo editing storage and would be my working copies of images, fully backed up with daily backup externally (on NAS).
B. Should I use RAID 5 or RAID 0? I'm looking to back up the array but a modicum of safety with sacrifice too much speed would be a good idea.
C. Should I keep partitioned drives? If so, 500GB?
D. Should I keep some space for a JBOD partition (thereby having all drives the same size, for other purposes, e.g., for a boot drive or other miscellaneous storage?
E. Will partitioning slow down the operation of the array?

A. What is the best configuration for speed? My use would be for photo editing storage and would be my working copies of images, fully backed up with daily backup externally (on NAS).

Striping is always fastest, but you would get great results with RAID 4.
Reads will be close to 3X of a single disk, writes will be fast also, see our performance numbers on our front page on the web site. (Priority: Data Access Speed)

B. Should I use RAID 5 or RAID 0? I'm looking to back up the array but a modicum of safety with sacrifice too much speed would be a good idea.

RAID 4 is best for SSD!

C. Should I keep partitioned drives? If so, 500GB?

This is up to you. There is no real need, unless your workflow is superior with multiple volumes.

D. Should I keep some space for a JBOD partition (thereby having all drives the same size, for other purposes, e.g., for a boot drive or other miscellaneous storage?

Maybe a small boot volume, then a 3 drive stripe for scratch with the "remaining" space. SSD's don't really need to be partitioned, otherwise.

E. Will partitioning slow down the operation of the array?

no.

Thanks for your suggestions. A couple more queries:
With RAID 4 or 5, in the event I have to rebuild after failure of one drive, heaven forbid, will different size drives still rebuild from the parity set?
Can the drives still be hot swapped if the enclosure blows it (and it does, it'll be an Akitio)?

As long as the replacement drive is the same size or larger, yes.

Yes, you can change enclosures (or even connected bus's) and not have any problems with the volume.

I know from your web site that the RAID 5 set up gives distributed parity, in theory, any drive that fails can be rebuilt with another, whereas in RAID 4, if the parity drive fails, rebuild isn't possible. So, is the throughput degraded in RAID 5? Why (else) do you recommend RAID4 as best for SSD? I'm less worried about the drivespace than in speed of the array and security of the data (e.g., having to start over unnecessarily).

Thinking that I can use the same drive in the striped array, with a small partition from the 1TB to make up a 4 drive array. I have a total of 4 SSD's two 1TB, two 500GB. Potentially I have a fifth drive in a separate enclosure that could be used as a swap drive in an emergency. Still sound good?

Your assumption about RAID 4 is incorrect. A RAID 4 volume can be rebuilt in the same manner as a RAID 5 volume.

RAID 4 reads are faster for SSDs because with RAID 5, the parity data has to be read, then discarded, while with RAID 4, the parity disk is ignored. Turns out this is not so important with HDD's but with SSD's makes a significant impact.

Don't quite understand your second question. But SoftRAID will support any configuration of volumes you want to create. With those 4 disks, you can create a 1.5TB RAID 4 volume (3 data disks and one parity) and a 1TB stripe volume.

My questions, it seems you answered it partially, was, suppose the parity drive (in this case,) the 500GB volume goes bad, can the disk(s) still be rebuilt? What is the function of the 1TB "Stripe Volume" supposed to be, in this configuration?

In re-reading the thread, I see that you may mean the Striped Volume is a 1TB RAID 0 volume added/striped with the RAID 4 volume. Is this what you are saying? Wondering, in this example
A. Is this arrangement is too convoluted?
B. What is the net storage available?
C. Most importantly, what is the throughput speed? With a T3 enclosure for the entire array I'm hoping for 3750MB/sec but will be happy with 2700MB/s. That corresponds to what you were speaking about before, about 3x the speed of a single drive T3 connection.

Your first question, if any drive fails, yes you can rebuild or replace the disk and rebuild from the remaining disks.

The idea about adding a 1TB RAID 0 was just to use the remainder of the drives for something useful.

No this is not too complicated. Total capacity is dependent upon the volume types, etc. Just remember every "partition" is the same size in a RAID volume and you can mix and match RAID types on the same disks.

C - you are not going to get 2GB/s with 3 drives. Each one probably only does 450-500 MB/s. (a 4 disk RAID 4 is essentially 4 drives)
SoftRAID will give you the max performance possible with your hardware, though.

Would a six "partition" array (two on the 1TB's, 1 on the 500GB) work better? I could optionally swap out some current, but older 500GB drives to attain precisely 4x 500GB if it results in a speedier system. The current crop of drives is brand new and probably a better idea, however I am concerned with throughput.