Getting the Correct setup

No, only one partition per disk per volume is allowed.

Don't try to make a complicated setup. Just use SoftRAID as it was intended!

There will be spare space on two of your drives because you have mismatched disk sizes. You can create a mirror or stripe on them, or ignore it. Your choice.

OK. Trying to keep it simple and max out the speed. How about 4x 500GB SSD partition's in a RAID and I'll ignore the rest (e.g., use remaining space partitions as JBOD). Will that work?

It seems I hijacked this thread from dougbitt. Sorry 'bout that.

No, only one partition per disk per volume is allowed.

Don't try to make a complicated setup. Just use SoftRAID as it was intended!

There will be spare space on two of your drives because you have mismatched disk sizes. You can create a mirror or stripe on them, or ignore it. Your choice.

I can move this to a new thread so as not to take over dougbitt's discussion further.

Look, I'm just trying to learn how to use the software effectively. You could've posted a list of these rules or directed me to the appropriate page. Instead you spoon-fed me.

I'm OK with that however, seems you are getting testy about something. Maybe I'm just sensitive about taking somebody else's thread. Anyway... Please understand I am coming at this from a hardware RAID experience. This is also a pre-sales question, OK?

Again, my situation is I want a fast array and have four drives of two different sizes to use (or if it doesn't work, could jigger something else). So, I can use one partition per drive, got it. What other limitations are there to the software?

If there aren't further limitations, you indicated (it looks like, to me anyway) I can use 4x 500GB SSD partitions, one per drive unit, in a single enclosure to achieve the cleanest, fastest throughput in RAID 0, or RAID 4 (using RAID 4 vs others for fast, yet rebuildable reliability).

Further questions we haven't discussed yet:
• Does rebuilding go on in the background when a new drive replaces a failed one (already formatted), like it would for a dedicated hardware RAID controller?
• What is the expected throughput of a 4 drive/partition SSD array as described (not making any guesses, here), in RAID 0? RAID 4? It will be housed in/connected via a Thunderbolt 3, 40Gb/s environment (as soon as it's available).
• Does this require a softRAID update of some sort to work?
• How long is the array out of service in the case of rebuilding with a single replaced drive in an 80% full array (approx. 1.5TB total space)? Can you detail the math to calculate this?
• What are the machine's RAM requirements/considerations during the above conditions (e.g., normal operations - reading/writing, restoring, not reading/writing)?
• Will the array be forced to sleep inappropriately by MacOS? What happens to wake time? Do you recommend or does the software fix any MacOS imposed sleeping issues so other drives can sleep and the RAID does not?
• Is there anything else to keep in mind - rules or requirements you haven't yet mentioned? Have we covered everything that you know so far?

If there aren't further limitations, you indicated (it looks like, to me anyway) I can use 4x 500GB SSD partitions, one per drive unit, in a single enclosure to achieve the cleanest, fastest throughput in RAID 0, or RAID 4 (using RAID 4 vs others for fast, yet rebuildable reliability).

Yes to both, you can use RAID 0 or 4. 4 has redundancy, 0 does not.

Further questions we haven't discussed yet:
• Does rebuilding go on in the background when a new drive replaces a failed one (already formatted), like it would for a dedicated hardware RAID controller?

You need to "add disk", but then all rebuilds are in the background.

• What is the expected throughput of a 4 drive/partition SSD array as described (not making any guesses, here), in RAID 0? RAID 4? It will be housed in/connected via a Thunderbolt 3, 40Gb/s environment (as soon as it's available).

We post this on the front page of our web site, using standard OWC SSD drives, different brands will get different results.

But you should be getting close to 1GB/s on RAID 4 (reads/writes) and nearly 1.5GB/s on RAID 0, depending on how fast your SSD's are.

• Does this require a softRAID update of some sort to work?

Update? Not sure what you mean. You need to install the SoftRAID driver to the latest version and keep it up to date, but otherwise, nothing special.

• How long is the array out of service in the case of rebuilding with a single replaced drive in an 80% full array (approx. 1.5TB total space)? Can you detail the math to calculate this?

Its never out of service in a RAID 4 volume, as rebuilds are background tasks. Rebuild speeds are based on optimization, but "server" optimization will rebuild as fast as the SSD can copy data. So it is not long.

• What are the machine's RAM requirements/considerations during the above conditions (e.g., normal operations - reading/writing, restoring, not reading/writing)?

Nothing special. RAID 4/5 does best with i7 processors, quad core or better. Every Mac Pro has about the same performance. Older/slower machines will lose a few percent of performance on RAID 4/5, not on RAID 0.

• Will the array be forced to sleep inappropriately by MacOS? What happens to wake time? Do you recommend or does the software fix any MacOS imposed sleeping issues so other drives can sleep and the RAID does not?

SoftRAID is not involved with the file system or sleep. So it does what OS X does.

• Is there anything else to keep in mind - rules or requirements you haven't yet mentioned? Have we covered everything that you know so far?

Download SoftRAID and try it, so you can see how it works. the trial period is 100% functional.

To answer your other question about Creating a 4 disk RAID 4 volume, yes you can use the remaining space as either two non RAID volumes, or create a stripe volume on that partition space.

To answer your other question about Creating a 4 disk RAID 4 volume, yes you can use the remaining space as either two non RAID volumes, or create a stripe volume on that partition space.

Thanks for all your assistance. I appreciate the time and answers. Looking forward to the trial period when I have my hardware in place. Wish they'd hurry up with a T3 solution (looking at Akitio & OWC to finally support Thunderbolt 3. Hint, hint anybody listenin??).

Henry

Results:
• I got the enclosure mentioned with the SoftRAID package.
• Was able to partition the 1TB as discussed: 1 @500GB JBOD and 500GB RAID Disk.
• Was able to combine the 500GB disks into 3 more member disks of the Volume making a four 500GB RAID 4 array.
• The base performance of each of the EVO 500 disks is 360MBps.
• The net performance of the RAID 4 in theory about 3x speed (~1080MBps?). I will measure it when it gets built and confirm.
• Had some issues with older disk (1TB) that didn't certify. It may be under warranty. So it is not in service at this time. On it's way back for replacement or reconfiguration.
With a parity disk, it's looking like 1500GB storage, plus the JBOD's @1500GB. Plus the 1TB (5ᵀᴴ drive), assuming it gets fixed.

It seems you are trying to create volumes in pieces.

Creating a RAID 4 volume is very easy:
initialize 4 disks.
Create the RAID 4 volume
Select the parity disk.

If one of the disks is larger, don't worry. You can either ignore the additional space on it, or create a non RAID volume on it to store data on that volume also. (non redundant)

Yes. Figured out the technique in SoftRAID and partitioned the larger disk in two halves. Then put half in the RAID volume, half in a separate non-RAID Volume. SO I used all the available space. Used the oldest (likely the slowest) disk as the parity disk in the RAID.

My measured speed of the array (in AJA System Test Lite) is a fairly constant 870-900Mbps write and 930-950Mbps Read. I have it set as a digital photography volume.

The independent volume is running at 358-380Mbps Write and 390-400Mbps Read.

The real world results seem a bit below what you indicated I should expect. Any ideas?

SoftRAID's driver has a latency in the low microseconds, so it can maximize disk performance. it is not a bottleneck. Writes can be limited with slower core systems, with RAID 4/5 because of parity calculations, not the case in your scenario.

You may be bumping into limits of Thunderbay, or the enclosure. Hard to complain about 900MB/s reads/writes, though. ;-)

Not a complaint, just lower than what you indicated. It works as advertised. I'm satisfied. And with redundancy. Wondering if I chose the correct settings, is all, optimizing for Digital Photography.

Showing two screen shots... The earlier one @09:58:30 is a single disk partition JBOD Volume inside the Thunderbay Mini 4 enclosure. The second@ 10:00:10 is the RAID 4 array. Both tests are in AJA System Test Lite with the same sample file sizes and types.

My files installed fine and seem to operate with no troubles. Somehow though, the RAID performance has gotten better in Read and worse in Write by itself, over time (a few days) from when the drive was first installed and tested while empty. Is there any reason for this? I did the same test when the drives were empty having just been built, as mentioned previously.

I verified these results with another system diagnostic BlackMagic. Read/write seems to agree.

Any recommendations to improve Writing performance?

Write performance is affected by several things, including data on the volume (fragments the writes, which is less of a factor with SSD, though), background indexing and any other tasks going on.

Its working as fast as the disks can work, for what that is worth. I don't think I can recommend anything special.

I improved the read/write speeds tremendously by repairing the array directory in DiskWarrior. Back to 700Mbps and 1100Mbps respectively.

There were also many files that were copied with incorrect user permissions in building the RAID. I had to manually repair those folders with incorrect permissions since I didn't want to mess with the root installed permissions on the drive. For some reason, the root permissions on a RAID or a JBOD Disk built in SOftRAID do not have any user permissions applied. Is this normal?