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OWC Accelsior 960GB SSD PCI - Thoughts

S

scottrichardson

macrumors 6502a
Original poster
Jul 10, 2007
718
297
Ulladulla, NSW Australia
Hi all,

I'm running out of disk space on mac 09' Mac Pro.

Currently running an OWC 240GB for boot/apps drive, and two 120GB Vertex 2 drives in RAID 0 for my projects and files. I also have a 2TB WD Black drive for my iPhoto and iTunes libraries.

It's my two vertex 2 drives that are almost full. 15GB left on the 240GB array.

All up I am storing around 410GB of files across all 4 drives. YES I have spare space on the WD Black drive, but I'd prefer to keep as much of my files as possible on SSD.

What I'd like to do is replace it all with one big disk, and the OWC Accelsior 960GB seems rather compelling - it's faster than SATA III, and it allows me to keep everything on one drive, allowing me to make use of the standard apple file system for storing documents, pictures, music etc etc.

Anyone got thoughts on this, and also any anecdotal experience with the 960GB Accelsior being used as a boot drive and files drive?

Scott
 
check macperformanceguide - he's posted quite a bit on these and loves them.

I've wanted one, but don't have the slots available so I'm using SSD hanging of my Areca card.
 
I have the 480 and it works amazingly well. What I would suggest, though, is that you keep one drive as a boot drive (a "normal" SSD) which still has a high rate of read/write small packets. Use the accelsior as a work-drive where you keep your files and a separate drive for boot only and/or software as well, this is where it REALLY shines.
 
Boomhowler said:
I have the 480 and it works amazingly well. What I would suggest, though, is that you keep one drive as a boot drive (a "normal" SSD) which still has a high rate of read/write small packets. Use the accelsior as a work-drive where you keep your files and a separate drive for boot only and/or software as well, this is where it REALLY shines.
Click to expand...

What about TWO Accelsiors?

One 240GB one for apps and OS, and a 480GB one for data?

Is there any real bottleneck in just having ONE 960GB one though? And using it for EVERYthing?
 
But the Accelsior card does work well as a boot drive as well, right?

I have an existing SSD, but I want to convert that one into a Bootcamp drive for Windows 7 solely... Then use BootChamp and BootManager to switch between OSX and Windows. Due to using a EVGA GTX680 for graphics card, I have no Boot screen on the Mac Pro...
 
scottrichardson said:
What about TWO Accelsiors?

One 240GB one for apps and OS, and a 480GB one for data?

Is there any real bottleneck in just having ONE 960GB one though? And using it for EVERYthing?
Click to expand...

hmm, not really, I would assume that (depending on your workload) you never will be bottlenecked by the accelsior. That said, you would totally eliminate any io-collisions if you use 2 accelsiors instead of one.

I'm trying to see if the sata-bus is using the same resources as the pci-bus. If that is the case then it wouldn't matter if you use 2 accelsiors or 1 pci drive and 1 sata. If they aren't, however, then you could be even more "on the safe side" if you use a normal SSD as a boot drive (on a sata connection) and the accelsior as a data/user-drive. This also makes it possible to be a bit more nice with over-provisioning on the boot drive to keep a constant performance, as long as you leave place for any swap-files which might occur if you have too little RAM.

edit: and if you are using a 2008 mac pro, the accelsior is not your friend if you try to bootcamp... also, two pci ports leave you one less for GPU or other expansion cards.
 
So I ordered the 960GB Accelsior yesterday! Can't wait for it to arrive.

I'm going to try running it as my sole drive.... but I will keep my older SSDs in the machine just in case I need them. I'll also keep my 2TB Black drive as an alternate Time Machine drive. But if all goes well with the Accelsior, I'll ditch the 3 SSDs I have in there and sell them.
 
The Accelsior is an elegant solution today, but it's waaay overpriced for what you get and it offers no real upgrade path as the SSD blades are non-standard.

You can get a Crucial M4 512GB drive now for $349... that's about half the price per GB of the Accelsior.

There are a few different SATA3 solutions available to get the most out of it, but to be honest, when I recently moved my OS/Apps M4 SSD from the SATA2 backplane to a Apricorn SATA3 interface, I didn't notice any change. This is perhaps not surprising, since most desktop usage particularly on a OS/Apps drive is small file random I/O.

I also had my photo libraries on a trio of old Intel SSDs in RAID0 on the SATA2 backplane and recently moved to a trio of larger, faster SATA3 SSDs connected to a Highpoint 2720 PCIe card... again, no real difference in real world... though it benchmarks beautifully. (Full story here).

So my advice to achieve copious fast solid state storage in a Mac Pro would be these solutions (rated from best-bang-for-the-buck to worst):

1. A pair of 512GB SSDs in RAID0 on the SATA2 backplane
2. A pair of SSDs in RAID0 using one or two Apricorn Solo x2
3. A boot drive on an Apricorn Solo x2 and other drives on a Highpoint (my current solution)
4. An OWC Acceslsior
 
I disagree. The Accelsior is a much faster solution than any single SSD. In addition to it being straight into the PCIe lane, it is not hampered by the lack of SATA3.

Even when compared to two SSDs in Raid0, when not via a PCIe Raid card, it is still slower than the Accelsior.

Only when running two SSDs through a Raid card will the performance match the Accelsior, but then there is not really a price difference, and you are running a Raid0, with all the issues that come with!
 
Killerbob said:
I disagree. The Accelsior is a much faster solution than any single SSD. In addition to it being straight into the PCIe lane, it is not hampered by the lack of SATA3.

Even when compared to two SSDs in Raid0, when not via a PCIe Raid card, it is still slower than the Accelsior.

Only when running two SSDs through a Raid card will the performance match the Accelsior, but then there is not really a price difference, and you are running a Raid0, with all the issues that come with!
Click to expand...

First of all, there's no magic to the Accelsior... it's a pair of Sandforce SATA3 SSD blades running in RAID0. They are the same OWC SSD blades that they sell for Mac Air upgrades. So you still have the added risks and issues with RAID0 using that card. And many would be even more reluctant to trust storage duties to Sandforce controllers.

The Highpoint 2720 card I use, is $140 and a pair of 512GB M4's is $700 so you can have the equivalent of the Accelsior for $840 which will save you about $660!!! Besides the savings, the benefit of this approach is that you're using off the shelf drives and can upgrade them anytime down the road... or add more drives for added capacity and performance. The only real advantage to the Accelsior is the convenience of the packaging... plug in and go... no cables, etc. A benefit for some.

Having said all this, I stand by my assertion that a couple of SSDs running in RAID0 off the SATA2 backplane are also blazing fast and I doubt very much anyone could realize the difference in moving to an Accelsior. I didn't and my 3 drive setup is at least as fast as an Accelsior.

So while the Accelsior has a place, I would still rate it last out of the four bang-for-the-buck SSD solutions available for the Mac Pro that I listed above.
 
I looked at Accelsior when it first came out but eventually settled on Apricorn's Velocity Solo x2 paired with an OCZ Vertex 4 512GB.

I edit video within Premiere CS6, Symphony, and FCP7 and wanted the speed of using the SSD as a scratch disk, in addition to already running an SSD(OSX) mounted in the lower optical bay running at SATAII; However, 512GB is quickly filled, even when editing compressed long gop formats like AVCHD natively, so I looked at purchasing a second Velocity Solo and another 512GB drive to stripe in a RAID0, but ever since the crush of Black Friday last year, the costs of 512GB SSDs have gone up over $100 from previous prices.

In another thread, someone had linked the Highpoint Rocketcache 3240x8, which enables you to pair a large capacity HD with up to 3 smaller capacity SSDs; Giving you the best of both worlds, the capacity of a large HD, the speed of SSDs in cache, as well not having to buy large capacity drives since the Rocketcache can only pull up to 64GB of cache from the SSDs. I installed the setup yesterday with a 3TB 7200RPM Seagate and three Intel 520 60GB HDs. I'm running the Max Performance setup and backup externally.

Digiloyd and AJA Speed tests average around 1200MB/s read and 1100MB/s write. This setup isn't for everyone and there is an added cost in purchasing the modified drive sleds from Maxupgrades, but there is an external version for this card.

http://www.barefeats.com/hard148.html#sister

Edit: I should also mention that this setup is non bootable.
 
Last edited:
Hey all.

Installed the 960GB Accelsior today.

I actually am a little disappointed - things feel less responsive and slower. While it scores faster in Black Magic Disk Test - the random reads, showing lists of thumbnails, displaying all my fonts in font case, icon thumbnails etc.. I noticed even apps take a couple more bounces to load.

So yeah.. a little flat after spending $1600 AUD on it :(
 
scottrichardson said:
Hey all.

Installed the 960GB Accelsior today.

I actually am a little disappointed - things feel less responsive and slower. While it scores faster in Black Magic Disk Test - the random reads, showing lists of thumbnails, displaying all my fonts in font case, icon thumbnails etc.. I noticed even apps take a couple more bounces to load.

So yeah.. a little flat after spending $1600 AUD on it :(
Click to expand...

Send it back and go with a pair of 512GB Crucial M4s in RAID0 on the SATA2 backplane and take your girl on a nice weekend away with all the money you saved. ;)
 
I have now used the Accelsior for a few days, and it is fast. Of course the boot time is fantastic, but so is application's loading. I moved my Aperture DBs to it (from a Crucial C300 SSD), and opening and navigating is literally 3-4 times faster.

The issue with boot menu I have found is not an issue. If anything gets mixed up, I use the recovery partition I have put on a USB stick to use a reboot menu which does see the Accelsior.
 
OK so I have done some further tests and had a little more time to play with it. I think at first I was just looking for faults.

I ran quick bench and the ONLY area where the Accelsior gets beaten by both my OWC 2G 240GB SSD, and My RAID 0 2 x Vertex 2 120GB SSD, is in the 4K test. 8K and up, the Accelsior streaks ahead. The bigger the data size, the further ahead the Accelsior goes.

- In the 4K test, we're talking 35MB/sec for the Accelsior vs 40MB/sec for the others. By 32K and up, we're talking double, triple the speed.

- Boot times are identical.

- Launching 1.6GB Photoshop A2 Poster was identical (cold start, first launch of Photoshop CS6)

- Rotating said Poster 180 was 3 x faster on Accelsior

- Duplicate said poster in Finder was 3 x faster on Accelsior

I'll continue to monitor the experience and report back.

Scott
 
scottrichardson said:
Has anyone here used the TRIM enabler on their Accelsior before?
Click to expand...

RAID controllers rarely pass along low level SATA commands such as TRIM. Additionally, Accelsior is primarily design to work with Sandforce drives which do not encourage TRIM commands, so it is hardly likely they used an exceptional raid controller that would pass them along.

The OS 'talks' to the card's controllers and that controller 'talks' to the SSD.
 
scottrichardson said:
Should I be concerned too much with the lower performance of 4K-8K blocks on the Accelsior compared to my other drives?

Scott
Click to expand...

SSDs and RAID0 arrays of them, like the Accelsior, can be optimized for small random I/O, large sequential I/O, or a compromise of both. I gather from your question that the Accelsior appears to be optimized for large block sequential reads and writes? What are you seeing exactly? Post some benchmarks... ideally with Quickbench.

I've owned different SSDs over the last few years, and they all have slightly different characteristics. Due to the large NAND blocks in my old Intel drives, they were happiest in RAID0 with larger stripe sizes (eg. 128K). My current Vertex 4s perform best with small 16K or smaller stripe sizes, and from what I've read the Crucial M4 likes a balance of 32K or 64K stripes. I'm not sure what the sweet spot is for the Sandforce drives on your Accelsior but they are essentially the same controller that's in a Vertex3 if you want to research it. However, I suspect OWC doesn't provide any control over the stripe size of the array on their card. It's probably fixed in firmware.

As you probably know or found out with this new card, RAID0 arrays also don't scale at all with small random I/O which accounts for most desktop usage, especially on an OS/Apps drive.

However, RAID0 arrays DO scale linearly on large sequential I/O which is ideal for saving, loading, and moving large media files.

This is primarily why I decided to run m OS/Apps on a stand-alone drive like the Crucial M4 which was well regarded for it's small random read performance. And then I put my photo libraries on a RAID0 array of Vertex4s which are among the best performing sequential I/O drives around.

The Accelsior has probably been setup for a balance that's neither ideal for small random I/O performance or large sequential reads/writes, but I'm sure your benchmarks will scream on the sequential stuff because of the RAID0 parallelism.

I also believe that the Accelsior uses a x2 PCIe interface, so that will bottleneck your performance somewhat, and then if it's in one of the two top slots on your main board, you need to consider what else is using PCIe bandwidth there, as the Acceslsior will be sharing those 4 lanes. However, it's worse than that, I found the top two slots to cap out at 1GB/s total (or about half of what they should be capable of) with my own RAID card. It only performed without bottlenecks on one of the bottom two slots (which are 16 lanes each).
 
Just for the record, there is also the Sonnet Tempo SSD Pro, which let's you build this thing yourself and might end up less expensive/with a higher performance if you use different drives than the OWC.
Tempo_SSD_Pro.jpg
 
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Giuly said:
Just for the record, there is also the Sonnet Tempo SSD Pro, which let's you build this thing yourself and might end up less expensive/with a higher performance if you use different drives than the OWC.
Tempo_SSD_Pro.jpg
Click to expand...

This is exactly what I've been waiting for... it's just a shame that it's $300. It should really only be about $100. However, even at this price, you can build the equivalent to a 1TB Accelsior for about $1K USD.

EDIT: One other thing to keep in mind when evaluating or benchmarking SSDs... particularly Sandforce based SSD's as in the Accelsior... they rely on data compression to achieve rated performance, so obviously perform best with compressible data (like programs and documents) and perform lower than expected when dealing with compressed media files (images, video, or audio). As a result, Sandforce based drives make great OS/Apps drives but are eclipsed by other brands when it comes to media storage duties.
 
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In a few reviews, they all mention that the Marvel RAID controller in the Accelsior is the element that is bringing down performance in the 4K chunk area.

How are we to know what the RAID controller is like in this Sonnet card??!
 
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