The folks over at Apricorn - a 26 year old company in SoCal - sent me their new PCIe Drive Array to review. A new video capture card requires higher bandwidth storage - over 100 MB/s sustained - so the timing was good.
You may recall the Plus HardCards that plugged into PC ISA slots. They were a convenient way to add drive capacity back when most systems weren't wired for a second drive.
Drive capacities today exceed what casual users need, decimating expansion drive demand. But for those with high capacity and/or bandwidth needs - such as video editors - some kind of an array or an SSD is a must.
But if you are going to capture 4:4:4 HD video at 200+ MB/sec, you're going to need a lot of capacity too. Which makes a disk-based solution more attractive - if it has the bandwidth.
Available in PCI and 4X PCI Express versions, and supporting SSDs as well as disks, the Drive Array can handle a lot of bandwidth.
The PCIe Drive Array Physically the PeDA is a full-size PCIe card with 4 2.5" SATA hard drives that cover the upper surface of the card. On the bottom there's the Silicon Image chip and not much else.
WD's new 12.5mm 1 TB drives are currently in qual. Those would take up 2 slots due to the extra thickness of those drives today - but imagine 4 TB of high performance storage in your system for less than $1,000.
The card is so large it wouldn't fit in a Mac Pro without removing the PCIe filler panel from the end of the card, installing it and then inserting the card. There may be a trick to mounting that I don't know or it may be that my Mac Pro 1.1 is too crowded: 3 of the 4 slots were already occupied.
When restarted the PeDA showed up on the desktop as a single eSATA drive. Due to bugs in the Silicon Image software I used the Mac's Disk Utility to configure the 4 drives as a AID 0 - there's no redundancy so no "R" - and ran speed tests.
Running the numbers
Apricorn claims write speeds of 234 MB/sec and read speeds of 239 MB/sec with 4 7200 RPM notebook disks. The results of my testing were remarkably close to Apricorn's numbers considering I used software
RAID and a different benchmark tool.
The Blackmagic Design Intensity Pro video capture card requires higher than a single drive's bandwidth for 4:2:2 - the numbers describe video color space - and their Blackmagic Disk Speed Test (BDST) utility tests storage bandwidth. It appears to load a 2 GB file into RAM and then read/write with large - 256KB? - blocks.
Using Disk Utility's default 32KB chunk size in a 4 drive stripe BDST achieved 213.8 MB/sec on reads and 201.5 MB/sec on writes. In comparison, a 2/3rds full 1 TB WDC 7200 RPM Black achieved 102.9/102.7MB/sec, while a half full WD 10k VelociRaptor also topped out at 103.9 on writes.
How full a disk is relevant because Hard disks *do* get slower with use. This benchmark info is meant to give relative performance info only.
The popular Xbench utility came up with slightly different numbers for the 32KB 4 drive AID 0. Sequential 256KB block reads topped out at an anomalous 178 MB/sec with writes at 202 MB/sec. Xbench used a lot more CPU during its testing which might be related to the lower read speed.
The software AID overhead was about 15-20%. Single drive writes topped out at 62 MB/sec while 2, 3 & 4 drive writes grew to 101, 156 & 202 MB/sec respectively.
What about using SSDs? You can and I'll be testing 4 Intel X-25s soon. Apricorn claims write speeds of 675 MB//sec on their web site. Based on what I've seen, they'll be close.
The Storage Bits take With notebooks outselling desktops the market for the PeDA isn't as big as it once was. But if you need either a lot of storage in a small form factor or a lot of fast storage the PeDA could be the answer.
In the next few weeks I'll review 2 more options: the SSD-equipped PeDA; and a low-end external 4 drive array. The goal is to determine the most cost-effective high-bandwidth storage.
I don't recommend RAID 5 on small arrays which is why I didn't test it on the PeDA. Either stripe (AID 0), or mirror (RAID 1), or mirror and then stripe (RAID 10). For video use AID 0 is fine if you backup the data to another drive every couple of hours.
Comments welcome, of course. Credit to Jackie Cunningham of Drive Savers for connecting the dots and taking "R" out of RAID 0. Long overdue. I'll return the review unit to Apricorn after I complete part 2 of this review.