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OK, so this is really weird. I ran HDTune on a newly set-up home-built computer and got the following readings from my drives in mid-November.

  1. SSD 154 MB/s
  2. RAID1 87
  3. RAID0 198 (software installs)
  4. RAID0 98 Swap drive

Today, in January, I run HDTune (same version) and get these results, in MB/s:

  1. SSD 186
  2. RAID1 98
  3. RAID0 241
  4. RAID0 98 (Swap drive)

Here are more details that HDTune reports on the SSD drive: HD Tune: OCZ-VERTEX Benchmark


Transfer Rate Minimum : 135.4 MB/sec

Transfer Rate Maximum : 219.4 MB/sec

Transfer Rate Average : 185.7 MB/sec

Access Time : 0.1 ms

Burst Rate : 187.3 MB/sec

CPU Usage : -1.0%

To get to my question: Why are my hard drives improving in performance? Most of my logical drives are in some form of RAID, except for the SSD. Will this performance ever deteriorate? Note, none of my drives are a hybrid drive that uses some form of SSD to enhance the write/reads on actual platters.

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Somebody had the reverse issue: – Rolnik Jan 16 '11 at 6:39

Windows SuperFetch, which monitors your usage of your computer and intelligently loads data from your drives at the right time to optimize performance, may be responsible for the performance increase.

Edit: Though I'm not sure about how SuperFetch may affect a synthetic benchmark, this is still a possibility.

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Wild guess: A recent windows update had new drivers installed for your system. A chipset graphics driver may also have influence on HDD speed (DMA issues).

But maybe you just forgot a seemingly innocent change to your system...

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