reducing writes : Java Glossary

Reducing writes to disk speeds things up, but reducing writes to SSD (Solid State Disk) both speeds things up and extends the life of the drive. SSDs (Solid State Disks) have only a limited lifetime controlled by how many times they are written to.

End User Techniques

Here are some techniques for end users to reduce writes:

• Turn on write caching. This means writes are procrastinated, consolidated and sometimes eliminated altogether. There is a built-in cach in Windows. You can turn it on by clicking Start ⇒ control panel ⇒ hardware and sound ⇒ Device Manager ⇒ disk drives ⇒ your SSD ⇒ Policy I don’t recommend disabling write cache flush. This will interfere with automatic NTFS (New Technology File System) recovery after a crash. There are third party write caches that may perform better.
• Turn off lastAccessTime tracking with:
  rem turn off last-access maintenance
  fsutil behavior set disablelastaccess 1
• Turn off legacy 8.3 filename maintenance. See instructions.
• Use a defragger designed for SSD, not one designed only for hard discs. Disk defraggers pound the disk with writes.

Programmer Techniques

Here are some techniques for programmers to reduce writes:

• Read an entire file into RAM (Random Access Memory). Process it. Compare the result with the input. Only if they differ write it back.
• Use the com.mindprod.lazy.Lazy class to track which files you have already processed successfully. You can bypass reprocessing these if they have not changed since they were last successfully processed.
• Use whacking huge buffers. RAM is cheap nowadays. Most of the time you can read the entire file in one I/O.
• When temporary data will fit in RAM, don’t bother writing temporary files.