[vdr] Re: Disk performance (was: vdr - some general questions)

[Emil Naepflein <Emil.Naepflein@philosys.de>]

On Fri, 26 Apr 2002 11:47:00 +0200,
tobias.meyer-janson@sign-lang.uni-hamburg.de (Tobias Meyer-Janson)
wrote:

> The HD is a Maxtor 4D080H4 80 GB IDE. I know it's not the fastest but I
> thought some DVB-Streams would be no problem for any modern HD.
> How can I check if the HD is the problem? As I mentioned earlier I have
> also often digital artefacts both in picture and sound.
> 
> Is it enough to switch DMA on (hdparm says it *is* on) or should I use a
> special DMA-Mode? I know different HDs and controller have different DMA
> features - is this configured automatically? I think default should be
> the fastest possible.

The Maxtor itself ist fast enough. I use 7 of them in my system and have
no problems after changing several things:

1. hdparm options 
You can play around with this options. Important is to enable dma, which
you have already done. Also interesting are the -u, -m, -c and -a
options. Important is also the -k option to keep the settings over a
reset.

2. reduce cutting speed
Cutting makes real heavy use on all resources in the standard system. To
limit the resource use I limited the cutting speed by adding a usleep()
in the cutting thread. This limits the necessary bandwidth on my system
to about 2-3 MB/s. Cutting takes much longer, but who cares.

3. Increase the video buffer size
You can increase the VIDBUFSIZE? in dvbapi.c to a larger value.

4. faster recordings menu
I use the ls command instead of find and this is considerably faster
than the find which is going along all the symbolic links to all the
disks in the system. Having about 300 files on 7 disks the find took
5-10 seconds if several recordings ran in parallel. The ls takes
normally much less than 2 seconds (Klaus, I know you don't believe that,
but it is true. ;-) ).

BTW, the mainboard I use is a GA-7ZXR3.0 with a 700 MHz Duron and SuSE
7.3.

Emil