Random Read/Write Speed

The four corners of SSD performance are as follows: random read, random write, sequential read and sequential write speed. Random accesses are generally small in size, while sequential accesses tend to be larger and thus we have the four Iometer tests we use in all of our reviews.

Our first test writes 4KB in a completely random pattern over an 8GB space of the drive to simulate the sort of random access that you'd see on an OS drive (even this is more stressful than a normal desktop user would see). I perform three concurrent IOs and run the test for 3 minutes. The results reported are in average MB/s over the entire time. We use both standard pseudo randomly generated data for each write as well as fully random data to show you both the maximum and minimum performance offered by SandForce based drives in these tests. The average performance of SF drives will likely be somewhere in between the two values for each drive you see in the graphs. For an understanding of why this matters, read our original SandForce article.

Desktop Iometer - 4KB Random Read (4K Aligned)

Random read performance was a strong suit of the old C300 and Crucial scaled back on it a bit when building the m4's firmware. The 0009 firmware improves performance a little bit but not tremendously. As we've seen in our previous reviews however, for desktop users being able to hit over 60MB/s in 4KB random reads doesn't translate into real world performance gains. All of the drives here do very well.

Desktop Iometer - 4KB Random Write (4K Aligned) - 8GB LBA Space

Random write performance also improved a little bit post update. The m4 is still incredibly fast here, easily the second fastest drive we've tested.

Many of you have asked for random write performance at higher queue depths. What I have below is our 4KB random write test performed at a queue depth of 32 instead of 3. While the vast majority of desktop usage models experience queue depths of 0 - 5, higher depths are possible in heavy I/O (and multi-user) workloads:

Desktop Iometer - 4KB Random Write (8GB LBA Space QD=32)

Crucial's performance doesn't scale up with higher queue depths like SandForce's. That's mostly because with highly compressible data sets, SF's drives don't actually write more as queue depth goes up. The controller has to do more deduping but as long as it can keep up, performance looks like it increases while physical writes to NAND don't. Most random writes on a desktop machine are going to be highly compressible, however most desktop workloads won't see sustained 4KB random writes at a queue depth of 32.

Sequential Read/Write Speed

To measure sequential performance I ran a 1 minute long 128KB sequential test over the entire span of the drive at a queue depth of 1. The results reported are in average MB/s over the entire test length.

Desktop Iometer - 128KB Sequential Read (4K Aligned)

Here's where we see some huge gains. The original m4 firmware posted sequential read performance lower than the C300. With the update to FW0009, performance now surpasses the C300 and comes in just slightly behind Intel's SSD 510.

Desktop Iometer - 128KB Sequential Write (4K Aligned)

Sequential write performance sees a small gain but nothing major here.


The Crucial m4 Update AS-SSD Incompressible Sequential Performance
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  • ckryan - Wednesday, August 31, 2011 - link

    As one of those Intel 510 owners, I wish Intel would release some differing firmware releases to enhance some aspects of drive performance (I for one would enjoy smaller read and write ability over top end speed the 510 has). It's good to see some improved performance with the M4 at any rate, and there weren't many fixes needed either. Between the Crucial C300 and m4, the Intel 510, and the Corsair P3, you can get some vastly different performance characteristics just on firmware alone.

    I don't regret buying the 510, but I do regret not saving some money and getting the Performance 3, a drive which recently was going for >$100 less than the 120 GB 510 on Newegg a few days ago. So all told, Micron powered drives are -mostly- the same, but there are some important differences -- mostly price. If you don't want a SandForce controlled SSD, get which ever one is cheaper.
  • cactusdog - Wednesday, August 31, 2011 - link

    The 256GB M4 is excellent value....
  • imaheadcase - Wednesday, August 31, 2011 - link

    Picked one up from newegg.com for $330. Its a awesome drive.
  • jdietz - Wednesday, August 31, 2011 - link

    I got this same deal. $1.30 per GB is excellent. As mentioned in the conclusion, there's probably little difference between this and more expensive drives.
  • radium69 - Wednesday, August 31, 2011 - link

    What counts most for me, is that the M4 seem very reliable. And all of the bad things really are solved. I'm very tempted to buy the 256GB one. Also for what you get, it's absolutely great.

    With the price they are currently offering it's a very competitive product, and we all know that competition is good. :)

    Also Crucial seems to have a great customer service, which is a mood point but still nice to know.

    With all of the trouble about sandforce drives, Corsair force 3, OCZ vertex 2 and vertex 3, I absolutely don't want to risk any data corruption/loss. Why spend more and have a greater risk? Why all the bleeding edge products, when you can get nearly same results for a much friendlier price.
  • GoodRevrnd - Wednesday, August 31, 2011 - link

    Yup. If the Samsung 830 turns out to be a disappointment I'll likely be picking up one of these.
  • damianrobertjones - Wednesday, August 31, 2011 - link

    "Improvement for intermittent failures in cold boot up related to some specific host systems."

    Intermittent? According to the forum AND my Elitebook it's EVERY single boot from off that causes the black screen of nothing'nuss.

    I just love how they worded that little bit there.

    Glad they've fixed the problem... or have they... 'Improvement'?
  • Patrick Wolf - Wednesday, August 31, 2011 - link

    Recently the 128GB M4 has been $180 or less on many sites, making it the best value.
  • Marlin1975 - Wednesday, August 31, 2011 - link

    Most were $160 and buy.com was $150 with coupon for the 128gb

    I could not pass up a non-sandforce 128gb for $150 shipped.
  • raducanon - Wednesday, August 31, 2011 - link

    Today 8/31/2011 at Newegg Shell Shocker Deal (between 10.00 AM - 12.59 PM PT ) the Crucial M4 SSD 128 GB will be $169.99 !!!!!!

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