I was recommended an app today that supposedly increases the r/w cache on the SD card. By default it's set to 128kb.

I'd imagine this works in a similar fashion to a BufferedReader (in java).

My questions are:

  • Does this really work as advertised? Will I see increased I/O performance?
  • What effect, if any, does this have on the SD card? Can it cause premature failure?

Below is the Android Market description for SD Speed Increase :

SD Speed Increase

This application allows you to make more powerful the using of SD Card. This is changing a parameter in a file system (thus the need of Root access) that manages the size of the cache on the memory card. By default, this value is set to 128 (kb) but it was found that changing this value in 2048 (kb), the performances are optimized, making read-write on our external memory faster. Many thanks to brainmaster, XDA Member that discover this. Note that if you reboot/turn off your device, you lose the setting that you did, so you can click on the dedicated box to allow this app to set on every boot the value that you choose.

This function may be not work.

Device: ZTE Blade. Rooted and running CyanogenMod 7.0

2 Answers 2


Here's the original XDA thread.

Basically, it shows a fairly significant improvement for some devices. 2048 kB might not be the best setting for your particular device, so you might want to experiment. I'm running it on my device and noticed a minor improvement; it certainly wasn't harmful. I'm not 100% sure but I would think it would not increase wear.


To me, it sounds like one of the many voodoo tweaks for every OS.

You'll find that a loud few % of users will proclaim it's effectiveness.
The silent majority won't

If there was an effective way to improve SD card speed then I'm sure the clever engineers at HTC or wherever would have implemented it.

Some of the "improvements" posted appear bogus: you can get 66MB/s read from an SD card? No: you can read from the cache at that speed. Non-cached access will be normal SD speed of course

For example, post 588


Also from XDA (actual title, BTW): Increasing readahead in a not completely retarded manner

  • I really agree with you on this, I feel that on the majority of cases you might end up wasting resources doing useless readaheads. And, as you mentioned, the engineers at Google, HTC, Samsung, et al are not stupid. Commented May 25, 2011 at 16:23

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