Proper storage solution. Promise Pegasus?

[Bob Zelin]

Promise will not send you an empty chassis. You spend the money, and they give you the drives. This is a very low cost of entry for a RAID array. The Pegasus comes standard RAID 5. You get about 600MB/sec in this configuration with the R6.

If you ask the question “how can I have something like this for $500 ?” – you can’t.

Your limitation in speed is the current Thunderbolt buss. If you are on a budget, you can’t beat a price like this. I would avoid Seagate drives, and go for HGST or Western Digital. Dont’ buy green drives, they won’t work.

Bob Zelin

Bob Zelin
Rescue 1, Inc.
maxavid@cfl.rr.com

[Jack Jackson]

Thank you for your revealing response. I appreciate it.

Your limitation in speed is the current Thunderbolt buss.
How do I have to understand this? I think Thunderbolt is capable to insure transmission rates up to 10Gb/s(~1.25GB/s). Aren’t the HDDs with it’s 600MB/s the limitation? Or do you mean the lag of accessing files via bus per se compared to internal drives? Until now I wasn’t able to test the real power of Thunderbolt – only wasted to single 5400rpm-Drives.

If you ask the question "how can I have something like this for $500 ?" - you can't.
When i started thinking about a decent storage solution, I thought into the blue about spending 4000€ (~5500$). The idea of a Low-Cost-Model came in useful when I read about the Pegasus.
Of course I ran intro somethink like the ‘A08S-PS’:
https://shop.mediav.biz/products/accusys-8-bay-raid-storage-8-16-or-24tb
But I can not see the advantage to invest so much more money. Please correct me if I’m wrong – I would if it is worth it. Anyway, the big advantage of this setup may be the possibility to upgrade to a second A08S-PS in the future and double the performance connected via PCIe HBA Card with Dual Port. Could I also achieve a performance boost by adding another Pegasus via Thunderbolt?

I would avoid Seagate drives, and go for HGST or Western Digital.The problem is that neither HGST nor WD ist on the promise compatibility list. I think using this HDDs will lead to a loss of warranty. Do you have bad experiences with seagate drives?

If you are on a budget, you can't beat a price like this.
Would you give me a hint in which direction I should inform myself without the limitation of a ‘low budget’. I’m overwhelmed by the number of good deals I have found in my recherche.

[Bob Zelin]

I work with a lot of drive arrays – drive arrays that are bigger than the Pegasus R6. With a RAID 5 group, you are simply not going to get better performance than 600 MB/sec (unless you do RAID 0, which I never do because of high failure rate of drives today). A Maxx Digital ThunderRaid with 8 drives may do about 700 MB/sec, but only after several seconds (which means nothing, because you can’t accept lag upon startup of a sequence that you want to play back). I know it says “10Gb/sec” – but I am telling you what happens in real life.

Promise will NOT sell you an empty chassis. Period. So no matter what I recommend, you can’t buy an empty chassis from Promise – warantee or not.

The Promise Pegasus IS low budget. If you are a student, I can empathize with you. But if you are a professional that charges for your work, and makes your living doing this, the Promise Pegasus is a bargain.

bob Zelin

Bob Zelin
Rescue 1, Inc.
maxavid@cfl.rr.com

[Jon Schilling]

Our customers see speeds of 900MB/s + read/write with this: https://www.proavio.com/index.php/products/desktop/eb800ms

We also sell it without drives.

Jonathan Schilling
Vertical Sales Manager
Proavio Storage by Enhance Technology Inc.
12221 Florence Ave.
Santa Fe Springs, CA 90670
Dir: 562-777-3498
Main: 562-777-3488 X106
Fax: 562-777-3499
Email: jon@proavio.com

[Bob Zelin]

our friend wants a Thunderbolt drive array – is the EB800MS a thunderbolt native interface, or is it miniSAS ? That requires a $900 host controller card for a Mac Pro ?

Bob Zelin

Bob Zelin
Rescue 1, Inc.
maxavid@cfl.rr.com

[Jon Schilling]

mini-sas & requires a host card.

Jonathan Schilling
Vertical Sales Manager
Proavio Storage by Enhance Technology Inc.
12221 Florence Ave.
Santa Fe Springs, CA 90670
Dir: 562-777-3498
Main: 562-777-3488 X106
Fax: 562-777-3499
Email: jon@proavio.com

[Chris Murphy]

The difference between the 10Gbps spec and real world experience is due to overhead. The 8b/10b encoding alone causes a 20% hit. Although, I’m surprised at some of the benchmarks cited in this article, even accounting for the fact they’re RAID 0, there still should be some overhead for transport, data and file system layers.

Decent article on the subject:
Theoretical vs. Actual Bandwidth: PCI Express and Thunderbolt

An n+1 member RAID 5 array seems like it could have about the same read performance as an n member RAID 0 array, but chunk size and parity computation adds overhead for writes. A particularly good (expensive) controller will have more optimizations for this than average controllers.