[LAU] Ardour Error: Hard disk too slow

[Paul Davis]

On Sun, 2007-08-19 at 22:14 +0200, Matthias Schönborn wrote:
> > A message like this really does mean that your hard disk can't keep
> > up with the demand for data. The cause of this however can come from
> > several sources. Since you are running several programs at once, most
> > likely synced together through the Jack transport, this means that they are
> > probably all trying to access data from the drive(s) at the same time, and
> > as you know, audio can be rather dense when uncompressed. So the solution?
> > It is often recommended to have a separate disk for recording audio and
> > whatnot to, that way, when linux needs to read info for running a program
> > it wont interfere with the audio data access on another disk. Of course
> > faster sata/serial disk drives will help as well.
> 
> Hm... that sounds a little bit disappointing, especially as I found out that 
> theres an SATA- disk in my laptop (Samsung X20). sudo hdparm -tT /dev/sda 
> results in:
> 
>  Timing cached reads:   1592 MB in  2.00 seconds = 795.96 MB/sec
>  Timing buffered disk reads:   96 MB in  3.06 seconds =  31.40 MB/sec
> 
> Shouldn't that be fast enough?
> 
> Are there any people here who are recording to systemdisks with no problems?

let me put it like this. the behaviour of disks & filesystems never
ceases to amaze me in its unpredictability. i recently built up a
machine for someone that had two identical samsung disk drives in it.
they were both formatted in the same way to hold ext3 filesystems. One
had the OS installed on it, the other was empty. the systemdisk was
incapable of recording even 6 tracks at once without this error; the
other disk could do 64 without breaking much of sweat. the difference? i
don't know, but if i had to point a finger i'd point it at the OS
install fragmenting the disk allocation in ways that made it impossible
for the filesystem to allocate new, large, contiguous blocks in an
efficient way. this is just a guess. i really don't know the reason.

the error message from ardour means *precisely* what it says: ardour was
trying to read/write data from/to the disk, and it was not happening
quickly enough. this could be the fault of the disk h/w, the filesystem,
the disk controller, or the kernel. or all of them.

--p