On Tue, 24 Jan 2006, Kai Makisara wrote: ... > One thing that can affect your comparisons is that the amount of data is > quite small compared to the drive speed. The startup delay may be a > significant factor in the timings (it differs depending on where the tape > is and what has happened before the test). Even taking this into account, > the speeds you see with 2.6 are too small. > I think I said this too weakly ;-) If you want to measure the streaming speed of the tape system, the test file must be large enough. It can take tens of seconds before a streamer starts writing and this time does vary depending on the tape position, tape, has the drive been reading/writing before, etc. You can verify this i you can listen what the drive is doing during the tests. You can also try writing very small files and measure the times. A rule of thumb might be to have a test data that takes one or more minutes to read/write. The HP LTO-3 raw speed is 80 MB/s without compression. So, for a one minute test you should have 800 MB of uncompressible data (or switch compression off). -- Kai - : send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
