OCZ RevoDrive 120GB PCI Express SSD

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OCZ RevoDrive 120GB PCI-E SSD

March 15, 2011 by Lawrence Lee

Product
OCZ RevoDrive
120GB PCI-E SSD
Sample Supplier
Street Price
US$270

Interface speed has always been an advertising gimmick in the age of magnetic storage, as hard drives never delivered enough performance to push the limits of the pipes to which they were attached. At the time they were released, ATA-133 did not provide any faster performance than ATA-100, and neither did SATA 3 Gbps over SATA 1.5 Gbps. However, with the rise of the SSD, bandwidth is starting to become an issue. High performance models are pushing boundaries, particularly when performance junkies combine two or more in RAID configurations.

The OCZ RevoDrive is a high performance storage product that uses the PCI Express bus to go beyond the limits of SATA. As a PCI-E 4x card, it can handle up to 16 Gbps — one PCI-E 2.x lane can push 4 Gbps. The card/drive uses a pair of SandForce controllers which are used in many popular budget SSDs such as the OCZ Vertex 2, Corsair Force, and G.Skill Phoenix series (all 3 Gbps models). The secret to SandForce's success is a fast compression scheme that lowers the amount of data to be written, resulting in a net performance gain. To boost speeds further and actually make use of the extra bandwidth, the RevoDrive uses a Silicon Image 3124 software RAID controller, allowing the two SSD partitions to work in tandem in RAID 0.

 


The box.


Packaging.

Not only does the RevoDrive use a bigger pipe than SATA, it frees up SATA ports to increase the total amount of storage in your system. Being a PCI-E 4x card, it requires a 4x or higher slot, so if your current motherboard has just one such slot occupied by a graphics card, you're out of luck. It should be noted that many current boards, even budget models, have a pair of 16x slots, often with the second one running at a reduced 4x speed. The RevoDrive is an expensive proposition, with the 120GB model retailing for about US$300 compared to just over US$200 for a 120GB Vertex 2.

Specifications: OCZ RevoDrive
(from the product web page)
Available Capacities 50GB, 80GB, 120GB, 180GB, 240GB, 360GB, 480GB
Capacity PCI-Express interface (x4)
Usage Primary boot drive or data storage
RAID Internal RAID 0
Dimensions 181.07 (L) x 21.59 (W) x 125.08mm (H)
Shock Resistance 1500g
Seek Time 0.1 ms
Operating Temp 0°C ~ +70°C
Storage Temp -45°C ~ +85°C
Power Consumption 3W Idle, 8W active
MTBF 2,000,000 hours
Warranty 3-Year
50-80GB Max Performance
Read Up to 540 MB/s
Write Up to 450 MB/s
Sustained Write Up to 350 MB/s
Random Write 4KB (Aligned) 70,000 IOPS
120GB-480GB Max Performance
Read Up to 540 MB/s
Write Up to 480 MB/s
Sustained Write Up to 400 MB/s
Random Write 4KB (Aligned) 75,000 IOPS

TRIM / Garbage Collection

The storage portion of SSDs is composed of NAND Flash cells divided into smaller units, blocks, that are separated into pages. A problem with the way SSDs work is that only entire blocks can be deleted, not individual pages. If you delete a file, the pages it occupies are marked for deletion and the SSD continues on its merry way. When new data comes in that needs to be stored on these pages, the other pages in the block storing good data (not marked for deletion) are moved to cache, the block is wiped, and the good data is rewritten (a process called write amplification) along with the new material. To make matters worse, SSDs do not keep track of deleted pages, and doesn't recognize their presence until it attempts a write to the block in question. As you can imagine, this can slow down performance considerably over time as the drive fills up.

Most modern drives support TRIM commands in Windows 7 that tell the SSD to perform write amplification preemptively at the time of deletion, i.e. when you empty the recycle bin or format the partition. A TRIM compatible drive has nothing but fresh pages to write to, and it never has to perform that extra read/write cycle on blocks to clean out deleted data, speeding up the write process. As there are many non-Windows 7 users out there, some drives have a garbage collection feature that actively hunts for blocks with junk data and cleans them up when the drive is sitting idle so as not to impact performance. Manufacturers can also provide a utility that can be manually run from time to time to accomplish the same thing.

Unfortunately, the RevoDrive's Silicon Image RAID controller does not support TRIM, nor does OCZ offer any form garbage collection. For some tech savvy users, this can be a deal-breaker. When we inquired OCZ about this, they claimed that the performance degradation over time should be negligible as the RevoDrive performs so well to begin with — an argument that does have some merit as SSD performance degradation is usually not substantial. However, it is noteworthy that the higher-end REVO X2, which uses four SandForce controllers rather than two, does support idle garbage collection.

CORRECTION: According to a spokesperson from OCZ Technology who contacted us after this review first went live, "neither the REVO or the REVO X2 support TRIM; however, because the drives are SandForce based, both have garbage collection." More on this later.


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