[linux-audio-user] Ardour, Jack, and 2.6 kernels + XRuns with the Audiophile 24/96 M-Audio

[Joel White]

Malcolm Baldridge wrote:

>>I'm using 4 Seagate SX118273LC (18G) drives in a software RAID-1, mostly
>>because I wanted to see what putting together a RAID was like (and at 
>>the time I bought them, the drives were relatively cheap).
>>    
>>
>
>Bad bad bad bad bad bad bad bad.   RAID1 is good for fault tolerance, and
>for read performance... but worse than a single drive's performance for
>randomised writes.  Software RAID implementations would give you worse
>performance on writes under all conditions, I wager.
>  
>
Wow, an 8 bad mistake! Actually, I always kinda wondered about that.  
This could actually explain a lot of my latencytest results: diskread 
latency performance was fine, but diskwrite and diskcopy was crummy.

Ok, so I dug up an ancient 0.5G Conner IDE drive I had lying around and 
kludged it in.  Clocks in at a paltry 2MB/s transfer rate with hdparm.  
I was able to record 8 channels with Ardour with JACK set at 128 periods 
with no xrun in sight - yeehaa!  I was about to plan on picking up an 
IDE/ATA drive tomorrow, but now I have something else to try first.

Thanks, Malcolm.

Joel

>Try a non-RAID volume in your tests.  Keep in mind that one write is
>triggering TWO writes in TWO transactions over the same SCSI card (and bus,
>probably).  This isn't going to be good for latency or bus utilisation.
>
>Before you rip out too much hardware (and hair), try it with a "simple"
>volume first.
>
>=MB=
>
>  
>