[linux-audio-user] The trouble with disks, part II

[John Anderson]

Or should that be part III? I can't remember. Whatever. Let the saga 
continue.

Several months ago, I posted here about my xrun problem. A brief 
refresher: MSI K7N2Delta mobo, Athlon XP2200+, 1Gb RAM, Adaptec 29160, 
Fujitsu 36Gb (MAN3367MP), Terratec EWS88MT, Matrox G550, 
linux-2.4.18-22, 2.6.[0-4]. With the invaluable help of various denizens 
of this list, I went through the list of possibilities from irq 
priorities to kernel patches to jack compile flags. Eventually somebody 
found an article about problems with the Adaptec 2940, and suggested I 
try an IDE drive. Which was about the only thing I hadn't done.

In the meantime I've moved house, cut my hair, set a date for my wedding 
and bought a car. So it being a time for major life changes, today I 
went and bought an IDE drive - Seagate Barracuda 40Gb (ST340014A). 
Ordinary off-the-shelf nothing special. Not even serial-ata. Walked into 
a shop and said "Hello, I need to buy a 40Gb IDE drive". Walked out 10 
minutes later.

Previously I couldn't even run at -n 2 -p 1024 without a glitch every 
few seconds, unless I preloaded the .wav files for the ardour session to 
get them in cache.

With the audio data (reiserfs) and the swap partition on the IDE drive 
I'm running jack at -n 2 -p 128 with ardour and 6-10 tracks and not an 
xrun in sight. I can play an *entire* session and not one xrun shows up. 
Woohoo! linux-2.6.3-mm2 FWIW, although jack got unhappy and kicked 
ardour off the graph when I added jamin and bounced the cpu to 75%. Not 
entirely unexpectedly.

What burns is that I bought the SCSI setup specifically for audio. 
Could've saved quite a bit of money. Ah well. Maybe I can sell it or 
something. I spose I could try to get hold of a non-Adaptec SCSI 
controller, but it seems like more hassle than it's worth.

Oh, and some hard performance numbers, disc0 is SCSI, disc1 is IDE:

bash-2.05b# hdparm -Tt /dev/discs/disc0/disc

/dev/discs/disc0/disc:
  Timing buffer-cache reads:   128 MB in  0.34 seconds =375.42 MB/sec
  Timing buffered disk reads:  64 MB in  1.31 seconds = 48.75 MB/sec


bash-2.05b# hdparm -Tt /dev/discs/disc1/disc

/dev/discs/disc1/disc:
  Timing buffer-cache reads:   128 MB in  0.35 seconds =364.73 MB/sec
  Timing buffered disk reads:  64 MB in  1.14 seconds = 56.05 MB/sec

bye
John