posted by steve | Category: Useful Items That I Forget |

Seems like I manage to forget that hdparm exists for getting stats on disks in Linux. In any event, device and cache read timings are quite useful from time to time.

For example, this is from a celeron web server with an in-use 40gb ide:
hdparm -tT /dev/hda
Timing buffer-cache reads: 128 MB in 0.35 seconds =365.71 MB/sec
Timing buffered disk reads: 64 MB in 1.17 seconds = 54.70 MB/sec

This is from a dual proc Xeon web server with two 80gb IDE, this test is on the drive that’s not in use, though the in-use drive was similar (2080MB on buffer-cache instead:
hdparm -tT /dev/hdd
Timing buffer-cache reads: 2100 MB in 2.00 seconds = 1050.00 MB/sec
Timing buffered disk reads: 174 MB in 3.00 seconds = 58.00 MB/sec

This is not so good. It’s a drive that I thought I was maybe having problems with sitting in a PIII fileserver:
hdparm -tT /dev/hdc
Timing buffer-cache reads: 788 MB in 2.00 seconds = 394.00 MB/sec
Timing buffered disk reads: 16 MB in 3.24 seconds = 4.94 MB/sec

The operating system drive in this box is SCSI and here are its results:
Timing buffer-cache reads: 784 MB in 2.00 seconds = 392.00 MB/sec
Timing buffered disk reads: 90 MB in 3.03 seconds = 29.70 MB/sec