Seasoning SSDs for Testing

Using multiple brands and models of SSDs heavily over the course of a year for real world use taught me a lot about their shortcomings. But for testing, an accelerated process is needed.

For this special report, all drives were brand-new. All drives were given the same “seasoning” to simulate real world use of a period of several months:

1. DiskTester fill-volume;
2. Erase;
3. DiskTester fill-volume;
4. Erase;
5. Clone 22GB system onto drive;
6. Virtual memory test (twice);
7. Erase;
8. Create 20 million 8K files.
9. Erase;
10. DiskTester fill-volume (final test).

Real world use can be more demanding than the above over the course of a year.

All MB/sec figures in this review are using Mac OS X file system APIs, not driver level or direct access times. In other words, performance that a real program can attain.

DiskTester fill-volume

The DiskTester fill-volume fills a volume with 1000 files, using 4MB writes. This is very “friendly” to a SSD because of the large writes, which cause no internal fragmentation..

Creating 20 million files

The last item, creating 20 million 8K files (DiskTester create-files), might seem excessive, but it is not. Rather it is an realistic way to simulate use over a period of months.

Installing Mac OS X and a few applications deposits 1/2 million files onto the drive, and there are many more disk writes to achieve that bootable system, along with subsequent system optimization writes.

With my own active software development, each day my build environment creates and deletes about 1/4 million files (thus at least a million files per week), with far more writes than that.

So 20 million files represents perhaps two months of use, and is thus eminently reasonable.

TRIM

The TRIM feature helps restore an SSD to its original performance. But this requires operating system support, and Mac OS X does not have it. PC users might fare better in keeping their SSD in good working order. Bottom line is that TRIM is a half-assed feature for inferior technology.