Promise Pegasus J4 or GRaid Thunderbolt?

[Rome Will]

Thanks for this post guys! I’ve posted this below in a similar thread…maybe it can help shed some light on the J4…I have some experience with it and I wanted to share…and I kind of need some help…any thoughts is much appreciated!!

Set up my J4 last night with 4x500gb Samsung 840 (regular not the Pro) SSDs…tested it with blackmagic speed test and got around 550 write and 640 read…but the SSD’s were in RAID 0 (all four were stripped to together on the J4)…

My problem is that the device is advertised for speeds of +750 write/read when using SSD in RAID 0 format…so am I doing something wrong?! I’ve heard something about removing the cache, enabling TRIM (etc…) but that wouldn’t cause such a hit to performance would it?

I’m thinking I need the Pro edition for Samsung 840 given the difference in technology (one uses TLC, the regular, while the pro uses MLC…)…

Or am I missing something here? Really need those +750 speeds (want to edit footage and don’t want to use proxies when doing 2.5k- haven’t edited in a while and that workflow is new to me…).

Again, thanks and hopefully this ends up helping somone as this device starts to get around in the mkt.

[Alex Gerulaitis]

[Rome Will] “Or am I missing something here? Really need those +750 speeds (want to edit footage and don’t want to use proxies when doing 2.5k- haven’t edited in a while and that workflow is new to me…).”

What’s the host system? Have you tried clocking a single 840 (not RAIDed) – have you been getting 500MB/s read speeds on those?

There are several potential bottlenecks with J4:
– individual drive speeds (500+MB/s reads, 300MB+/s writes with 512GB Sammie 840), accounting also for performance degradation associated with age, fill rate, etc.
– TB speed limit of 10Gbs (1.25GB/s) and its (very small) processing / driver overhead
– OS / host system and software RAID overhead

My hunch that it’s the host system that can’t keep up. Let me know what you get from individual SSD benchmarks and when you stripe, say, two or three (rather than all four).

[Rome Will]

Hey Alex really appreciate you responding!! Thank you!

So, I believe when you’re asking me about my Host system you want to know about the computer that’s feeding the J4 (right?)…I’m running a MBP 2011 (Late) with 16GB of ram. It’s an i7 quad-core processor (I think it’s Ivybridge not the new SandyBridge)…I installed a 500GB SSD for my internal drive- another Samsung, but that one was a 830 model.

I went ahead and ordered a set of 4x 500GB 840 Pro SSD’s and another Pegasus J4 to compare to the one I’m having trouble with now (a J4 with 4x 500GB Samsung 840 non-pro SSD’s)…I’ll return whichever set lets me down the most (based on the added costs of the 840 Pro’s, or if the speed is the same and it’s just something wrong with my system)…

As for the the individual speed drive test- I think I already tried that…I’ll give it another go tonight but from what I remember, a single SSD gave me around 300/400 write/read speeds through thunderbolt into the J4…but I was frustrated last night so when I get home tonight I’ll give it another try and let you know.

Thanks again! Oh, and I talked to Promise customer support and all they said was the 840’s weren’t supported, and to try another benchmark test…and that the speeds of the J4 (which are advertised at +750 write/read) are just their test results and aren’t real world results sometimes…O_o…oh, ok…lol!

[Alex Gerulaitis]

Thanks for doing the tests and sharing your findings – much appreciated!

Another potential bottleneck is the SATA controller inside J4…

300/400MB/s write/read speeds sounds a little low for an 512GB 840, especially if it’s new: supposed to be 330/520. When you benchmark, do at least three runs, preferably after a restart.

What are the speeds of your internal 830?

[Rome Will]

My internal SSD tests around 350 write and 450 read…which I’ve heard was pretty consistent for the Samsung 830 SSD…I think the SATA controller allows me to hook up 6GB SSD drives…I’ll check again…

To make thinks worse, my co-worker just got a MBA- the new 2013 kind…I told him to run the Blackmagic app to test his computer…he pissed me off lol! He’s pulling in +650 write and +700 read…guess I should just buy a couple MBA’s and start editing that way…could save some money!

[Alex Gerulaitis]

[Rome Will] “he pissed me off lol! He’s pulling in +650 write and +700 read…”

That’d piss me off too. 🙂 These MBAs don’t use SATA – they use PCIe SSDs which do away with the SATA 6Gbs speed limit. I wouldn’t be surprised to see them clocking 1GB/s in near future.

Not sure how these MBAs would fare for serious editing though given their relatively slow integrated graphics and limited memory.

If there a way for your coworker to run a test on your J4?

[Rome Will]

Ok Alex…Im at now and I did like you said…here goes:

1) I unplugged each SSD and ran them individually through thunderbolt to check their speed…I didn’t do this through the J4, I did it through a Seagate adapter which had thunderbolt connection…and each drive came up around 384 Read and 305-310 Write

2) Before I took the 840 SSD’s out the J4, I tried to do a 2 stripped RAID and got speeds around 480 write and 650 Read…which means that as I add more SSD’s I get slightly faster Writes…but my Reads (which are kind of more important) max out at 640/650 after I RAID anything above 2 SSD disks…

3) This sucks…Like I said, I use a MBP 2011 i7 with 16 gb of memory…really wish I could reach the 750 speeds with the Pegasus J4…but something seems to be holding up the READ speeds…Im hoping that the 840 Samsung PRO’s I have coming tomorrow will help with the Write speeds..

Will keep you posted. Thanks again for the help/advice…anyone else have any ideas on whats creating the- as Alex said- bottleneck for my SSD speeds?

I’m going to do some more research and see if those things like turning off TRIM, etc…can help with the SSD speeds…

Rome

[Rome Will]

And yeah Alex…the PCIe looks like the move…I see OWC has the HELOS thunderbolt for sale with a 900gb PCIe SSD…but that might be a little much for 2 TB which is what I want…thats $3k…vs. my $2K for 2TB at 640 Read and 550 write…and there’s no guarantee that Ill get the advertised speeds for the PCIe SSD cards…

[Kevin Rag]

Wow! The J4 with 4 Sammie 840s would set you back quite a bit. It’s actually more expensive than the Pegasus R4 8TB with HDDs. But for such speeds in a small form factor, it’s only the J4 I guess.

Kannan Raghavan
The Big Toad Films Pte. Ltd.

[Rome Will]

Yeah @ Kannan, it set me back around $2100…$1800 for the 4 Samsung 840’s and the rest for the J4 (ended up keeping the Pro’s and sent back the regular 840’s…can tell the difference with the write speed, but not that much once its in RAID 0)…

We’ll see in the long run if it pays off…and you’re right, I could have opted for the R6 at >$2k…but even in RAID 0 I doubt I’d get >600 read/write…with this, I am.

If anyone is able to break >700 like the advertising says (and I’ve seen benchmarks floating around the internet) I’d REALLY like to hear…for some reason, I’m stuck on 600 write and 650 read with my 4 SSD 840 Pro’s stripped…sucks…really wanted the max speed. But I guess it is what it is.

I’ll try to get the Lacie Big Disk (Thunderbolt) to have as my backup for this J4…slower, but will do the good job for the redundancy needed…