linrunner/TLP — Issue #5: SSD issues
Author: ahoffmeyer3
Created: 2012-03-10 06:22:15+00:00
State: open

Your documentation mentions that the hdparm power saving features don't affect SSDs because they are ignored. I don't think this is true. I've been troubleshooting slow SSD write speeds on battery power, and I've narrowed down the issue to hdparm power saving settings. At power setting 1 (hdparm -B 1 /dev/sda), I get around 30 MB/s sequential write speeds (tested using something like dd if=/dev/zero of=tempfile bs=1M count=1024 conv=fdatasync,notrunc). When I disable power management in hdparm (hdparm -B 255 /dev/sda), my write speeds return to ~170 MB/s. The defaults in tlp are for 128 on battery and 254 on AC power.

I have confirmed this issue (with hdparm) with a friend who also has a thinkpad with a SSD (he has an x120e and I have an x201s). This problem also occurred on my machine with two different SSDs (samsung oem model that came with the thinkpad and Crucial M4).

Thanks for the great work you do with TLP!