Improve modem connection under heavy disk activity 3706

Dances With Crows

Worked a charm.

Before any tuning, both drives had: multcount = 0 (off) IOsupport = 0 (default 16-bit) unmaskirq = 0 (off) usingdma = 0 (off)

I got the following average results: hdparm -tdev-hda: 3.0Mb-s hdparm -tdev-hdd: 3.0Mb-s

Now I have tuned with these commands: hdparm -c1 -u1 -m16 -d1dev-hda hdparm -c1 -u1 -m16 -d1dev-hdd

Both drives now have the settings: multcount = 16 (on) IOsupport = 1 (32-bit) unmaskirq = 1 (on) usingdma = 1 (on)

I now get the following average results: hdparm -tdev-hda: 29.5Mb-s hdparm -tdev-hdd: 25.3Mb-s

That's an improvement of about 600%. I know that's only for sequential reading, but still it's pretty large. Most of the improvement came from the DMA setting. The unmaskirq setting did nothing to speed but prevented hard drive activity interfering with other io - in particular the serial port and modem combo. The hdparm command doesn't seem to be one that many people are familiar with. It pays to investigate it.

Of course you are right, I didn't read the man page properly and just buttumed it was the same as dma - on or off.