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Performance on Mac Pro with eSATA

Last updated January 31, 2011 - Send Feedback

Both the GMax Mini and the Elite-AL Pro Dual Mini are quad-interface solutions, implementing RAID. The bridge board required for the quad-interface does not allow peak SATA performance as with a straight-through design (eSATA only), and so performance will never reach the peak speeds that eSATA by itself allows.

The SATA cable itself limits throughput; while dual SSDs in RAID-0 stripe mode are capable of over 500MB/sec (in a Mac Pro), I have never measured more than about 272MB/sec over a single SATA cable, and the theoretical limit is 300MB/sec.

Want fast everything? Then you want the MPG Pro Workstation.

Speed limits by connector

When connected with Firewire 800, none of the drives can exceed about 84MB/sec in the very best case, since that is the limit of Firewire 800 performance. In reality, 65MB/sec writes are the norm, well below even what a hard drive can do, let alone an SSD.

Performance: RAID-0 stripe across the volume

Performance was tested using the FirmTek SeriTek 2ME4-E eSATA card on the 3.33GHz 6-core Mac Pro Westmere. The FirmTek card is a high performance 4-port eSATA card capable of extracting top speed from any external device.

Mercury Elite-AL Pro Dual Mini with 2 X 200GB Mercury Pro RE SSD
RAID-0 stripe

A flawless performance makes this the premium choice for anyone looking for top performance and reliability. This is as good a performance as you’ll find in any external quad-interface drive.

What’s not measured or evident here is that the transactional throughput of the solid state drives is even more impressive, as excellent as this performance is, applications involving intense disk usage will benefit even more from the ability of the solid state drives to soak up thousands of requests per second.

Average write: 221.3
Average read:  232.9

performance of Mercury Elite-AL Pro Dual Mini with 2 X 200GB Mercury Pro RE SSD
Performance writing 1000 files to fill the entire volume capacity
disktester fill-volume

Guardian MAXimus Mini with 2 X 200GB Mercury Pro RE SSD
RAID-0 stripe

Write and read speeds are slightly lower than the Mercury Elite-AL Pro Dual Mini, above. This is consistent with the RAID-1 results further below— the GMax runs a little slower.

Average write: 219.5
Average read:  221.9

performance with Mercury Elite-AL Pro Dual Mini with 2 X 750GB 7200 rpm Seagate as RAID-0 stripe
Performance writing 1000 files to fill the entire volume capacity
disktester fill-volume

Guardian MAXimus Mini with Seagate Momentus 750GB
RAID-0 stripe

The fast hard drive solution shows considerable read speed variation, though write speed is very consistent.

Laptop drives aren’t really designed for sustained use, and in normal use (e.g., sporadic access), perhaps performance would show less variation. The variation seen here isn’t too important in general, as this is still a very high level of performance. But for those who need consistent high performance across the entire drive capacity, the SSD solution is a far better choice.

The falloff in speed over the drive is normal, see Why You Need More Space Than You Need.

Average write: 169.8
Average read:  135.2

performance with Mercury Elite-AL Pro Dual Mini with 2 X 750GB 7200 rpm Seagate as RAID-0 stripe
Performance writing 1000 files to fill the entire volume capacity
disktester fill-volume

Performance: RAID-1 mirror across the volume

Since a RAID-1 mirror makes identical copies in real time onto two drives, performance can be expected to be less than a RAID-0 stripe, except that a single SSD is already maxing-out the cable and bridge board.

Mercury Elite-AL Pro Dual Mini with 2 X 200GB Mercury Pro RE SSD
RAID-1 MIRROR

Performance as a RAID-1 mirror is only slightly lower than with the RAID-0 stripe.

Since just one OWC SSD is really capable of about 270MB/sec, the bridge board and SATA interface impose a hard limit on performance somewhat below that of a single SSD. But that is a transfer rate limit, and definitely not a limit for any kind of random access performance, or intensive load consisting of thousands of reads/writes per second.

Average write: 215.6
Average read:  219.4

performance with Mercury Elite-AL Pro Dual Mini with 2 X 750GB 7200 rpm Seagate as RAID-0 stripe
Performance writing 1000 files to fill the entire volume capacity
disktester fill-volume

Guardian Maximus Mini with 2 X 200GB Mercury Pro RE SSD
RAID-1 MIRROR

Using the exact same 200GB SSDs, which I swapped into the GMax Mini, write performance is 1.5MB/sec slower, but read performance is 17MB/sec slower than with the Mercury Elite-AL Pro Dual Mini. I have no explanation for why this should be so, but it is consistent with the hard drive results that follow.

Average write: 214.3
Average read:  202.5

performance with Mercury Elite-AL Pro Dual Mini with 2 X 750GB 7200 rpm Seagate as RAID-0 stripe
Performance writing 1000 files to fill the entire volume capacity
disktester fill-volume

Mercury Elite-AL Pro Dual Mini with Seagate Momentus 750GB
RAID-1 MIRROR

Very good performance which is close to the peak speed of the hard drive itself.

In theory, reads from a RAID-1 mirror should be up to twice as fast as a single drive, because the reads can be striped, as with a RAID-0 stripe. That is unfortunately not the case with either unit, since with the hard drive setup, observe that reads and writes are all but the same speed.

The falloff in speed over the drive is normal for hard drives (but not SSDs), see Why You Need More Space Than You Need.

Average write: 86.2
Average read:  82.4

performance with Mercury Elite-AL Pro Dual Mini with 2 X 750GB 7200 rpm Seagate as RAID-0 stripe
Performance writing 1000 files to fill the entire volume capacity
disktester fill-volume

Guardian MAXimus Mini with Seagate Momentus 750GB
RAID-1 MIRROR

Very good performance which is close to the peak speed of the drive itself. See note above on read speeds, etc.

As with the SSD variant, the Guardian Maximus Mini is performing a little less well than the Mercury Elite-AL Pro Dual Mini, above.

Average write: 84.7
Average read:  78.7

performance with Mercury Elite-AL Pro Dual Mini with 2 X 750GB 7200 rpm Seagate as RAID-0 stripe
Performance writing 1000 files to fill the entire volume capacity
disktester fill-volume


Up to 960GB of Storage!

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