Crucial M4 256GB Review

Performance Analysis

In AS SSD’s sequential tests, the M4 happily achieved its headline speeds and then some, with a 426MB/sec sequential read and a 287MB/sec sequential write. This is an impressive level of performance and makes the M4 256GB the fastest SSD we've tested. However, when we previewed the OCZ Vertex 3 256GB, we found that drive produced a 506MB/sec sequential read and a 284MB/sec sequential write speed in the same test, so the M4 is unlikely to hold the title of fastest SSD for long.

More worrying is that the random read speed of the M4 is slower when dealing with single-queue depth and 64-queue depth reads than the C300 256GB. With only one operation to handle (single-queue depth), the M4 managed a random read speed of 22MB/sec rather than the 29MB/sec of the C300 256GB. With a queue depth of 64, the M4 managed a random read speed of 158MB/sec rather than the 216MB/sec of the C300.

These tests use 4KB files, the most commonly read and written size of file, so it was a shame to see the slower speeds from the newer drive. However, it's important to note that these speeds are still much faster than those of a hard disk; it's just that the differences between the two Crucial SSDs aren't as large as we'd hoped.

In ATTO, the M4 was again not entirely convincing against the C300 256GB. In the 4KB sequential read test, the M4 recorded a speed of 169MB/sec compared to the C300 256GB's 194MB/sec. The M4 only really displayed its superior read performance with larger 1MB sequential writes, where it produced read speeds of 430MB/sec compared to the C300 256GB's 368MB/sec.

The M4's write speeds in ATTO were noticeably quicker than those of the C300 256GB, with a 4KB sequential write speed of 230MB/sec to the C300 256GB’s 188MB/sec. As the majority of writes on a consumer PC are 4KB, this bodes well for real-world performance.

TRIM Performance

After disabling our test system's TRIM function, filling the M4 with data and then deleting it, we expected to see a considerable drop in drive performance. While sequential read speed as measured in AS SSD only dropped slightly from 426MB/sec to 422MB/sec, sequential write speeds in the same test dropped from 287MB/sec to 256MB/sec; an 11 per cent drop.

Random write speeds with a single-queue depth also dropped by 5 per cent from 79MB/sec to 75MB/sec. Thankfully, re-enabling TRIM and running a sweep of the drive saw performance return largely to normal although an AS SSD sequential write speed of 276MB/sec was still 10MB/sec slower than our first clean run through.

Conclusion

The M4, despite its rebranding, is only a minor update to the C300. Despite the slightly updated and re-tuned controller, the additional sequential read and write performance has come at the cost of random read and write performance. The M4 is a very fast SSD, but we'd hoped for more. However, this 256GB drive is still the fastest SSD we've reviewed, and it's actually cheaper than the C300 256GB, making the older drive redundant. Hopefully this is also a sign of things to come from drives based around 25nm NAND.

While it isn't worth upgrading from a C300 to an M4, the latter is still an excellent drive. However, from our preview, the Vertex 3 looks to have the beating of the M4 across the board, so expect a review of that drive soon.