As per our news item ten days ago, OCZ had been the object of customer criticism when it changed the Flash NAND MLC used in its Vertex 2s. The change had a significant impact on performance with data that can’t be compressed and sequential write speeds are down from 140 and 70 MB/s on the 34nm 120 and 60 GB versions to 70 and 35 MB/s on the 25nm versions! This difference is linked to the use of 8 GB chips in place of 4 GB chips. There are therefore fewer chips and the SF-1200 can no longer use all its channels.
OCZ is still announcing sustained write speeds of 275 MB/s on these models, basing these claims on results obtained on data that can be significantly compressed. Although not essential in terms of system disk usage, sequential write speeds may therefore be close to 8x less rapid with non compressible files with the SandForce controller!
What is more problematic for system disk usage is that the available capacity of these SSDs has also been revised downwards, with a larger proportion of the memory being reserved for the controller to ensure the reliability of SSDs using 8 GB chips. Only the 60, 90 and 120 GB versions are affected:
- OCZSSD2-2VTXE60G: 55 GB or 51.2 GiB usable from 64 GB de Flash
- OCZSSD2-2VTXE90G: 85 GB or 79.2 GiB usable from 96 GB of Flash
- OCZSSD2-VTXE120G: 115 GB or 107.1 GiB usable from 128 GB of Flash
The Vertex 2 product page has been updated (see Usable capacity breakdown) to take this into account but OCZ persists in listing the SSDs as 60, 90 and 120 GB versions in addition to the product references. On the 3"1/2 product page, only the 120 GB version is given as having a real capacity of 115 GB. Is this to say that the 90 GB 3"1/2 uses 4 GB chips?
While OCZ has put an exchange option
into place for anyone who desires it, a good initiative, we can’t say we’re satisfied with the current situation. That the sequential write speeds announced correspond to a specific case and can, in other cases, be between four and eight times slower, is already problematic, but that the real capacity of these SSDs is not given in the official product designation, is not acceptable!
With OCZ iself not reacting to the issue, we can only hope that resellers will have the grace to update tech specs and product names to reflect the real capacity of products on sale. This isn’t yet the case, even though stores are now very much aware of the misleading spec.
Unless justified by the difference in price, we advise you to go for the Corsair Force F60/F120s which use 34nm chips, if you want to stay with the SandForce SF-1200, or otherwise for a Crucial C300 based on the Marvell controller.