Real-World SSD Performance Considerations (Introduction)

Solid state drives (SSDs) are gaining widespread attention for their many positive qualities: high speed, no moving parts, reliability, etc. For more on SSDs, see the these pages, especially the SSD overview page.

Real world performance

Real-world performance of a solid state drive means two main things:

1. Speed compared to alternatives such as a hard drive;
2. Speed over time as the drive gets used (1/3/6/9 months later).

This special feature concentrates on item #2 above.

What they don’t want you to know.

Feels good at first, then degrades. Read this special report to understand the issues before you buy.

Rules of thumb for buying an SSD

Don’t be suckered.

The honeymoon might feel good, but 3/6/9 months later you might want a divorce! Many SSDs just don’t hold up with use. They can hold up just fine for casual use (web, email, etc), but become badly degraded in other scenarios.

Don’t buy just any SSD. These things cost money! Do your research. Some are far slower than others (even when new), including those offered directly by Apple in new Macs.

Many SSDs degrade in performance with use. They offer a quick “high”, with a hangover. But if you have such a drive, you can recondition it to bring performance up to a better level.

Many SSDs have a limited lifespan. Some simply crap-out without warning, because they have no over-provisioning for bad blocks. Others suddenly go into read-only mode. Don’t waste your money on a future coaster for your martini.

RAID-0 striping is not advisable with SSDs not rated for it (striping splits file blocks between drives, so failure of one drive is a complete failure). RAID-1 mirroring or spanning (JBOD) is OK because file data is not split across drives.

Favor SSDs with over-provisioning. Over-provisioning (OP) sets aside extra storage for bad blocks and helps maintain performance. OP reduces usable capacity, but is worth it. Drives that have 0% over-provisioning (yes zero percent) are OK if your only use of the computer is light-duty (web, email, etc).