SCSI error : Running low on SCSI DMA buffers

SCSI error : Running low on SCSI DMA buffers

Post by RHS Linux Us » Mon, 11 Aug 1997 04:00:00



 I get this error    Warning: Running low on SCSI DMA buffers
The error floods the screen and sometimes hangs the machine.
This usually happens when I'm doing some heavy reads on scsi
cdroms.  

I'm using an Adaptec aha1542 scsi adapter with a toshiba cdrom
and a yamaha cdr.  Could the adapter be causing this error?
I'm running debian linux kernel 2.0.30 on a 486 w/ 24 megs of ram.

I can sucessfully read from the scsi devices and even write cdroms.
Sometimes the machine hangs though.  And I waste recordable cds.

 
 
 

SCSI error : Running low on SCSI DMA buffers

Post by Ian Flintof » Wed, 20 Aug 1997 04:00:00


We have had the same problem using a AHA1542CP card with a 4.3Gb IBM
SCSI-II hard drive and Philips CDD2600 in an external box under
Slackware 3.1, kernel 2.0.29 and 30.

The system seems to be stable for a while then wham - screens full
of "running low on SCSI DMA buffers" followed by a kernel panic.
I posted to this group about it a while back.

Have you got any/all of the scsi stuff complied as modules? A
friend suggested it could be something to do with the buffers
needing concurrent memory which can become hard to find after a while
on a low memory system - sorry don't know the details. Our PC only
had 32Mb physical and 20Mb to buffer a single 4.3Gb partition on the
scsi drive. (due to a theft my 486 was temporarily acting as a
file server for around 15 machines).

After recompiling the kernel with all scsi stuff hardwired in the
system seems to have become much more stable. Got an up time of
6 days and have written several CDs and given the hard drive a
thrashing without problems so far.

I'd be interested in anything you find out about this problem

Cheers

Ian


>  I get this error    Warning: Running low on SCSI DMA buffers
> The error floods the screen and sometimes hangs the machine.
> This usually happens when I'm doing some heavy reads on scsi
> cdroms.

> I'm using an Adaptec aha1542 scsi adapter with a toshiba cdrom
> and a yamaha cdr.  Could the adapter be causing this error?
> I'm running debian linux kernel 2.0.30 on a 486 w/ 24 megs of ram.

> I can sucessfully read from the scsi devices and even write cdroms.
> Sometimes the machine hangs though.  And I waste recordable cds.


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SCSI error : Running low on SCSI DMA buffers

Post by Bryan Armstro » Fri, 05 Sep 1997 04:00:00


I have the same problem with an NCR406a SCSI controller
and CD-ROM.  I recompiled everything SCSI into the kernel
(instead of loadable modules), and everything got better.
I'm using kernel 2.0.25.

-Bryan



Quote:>We have had the same problem using a AHA1542CP card with a 4.3Gb IBM
>SCSI-II hard drive and Philips CDD2600 in an external box under
>Slackware 3.1, kernel 2.0.29 and 30.
[snip]
>>  I get this error    Warning: Running low on SCSI DMA buffers
>> The error floods the screen and sometimes hangs the machine.
>> This usually happens when I'm doing some heavy reads on scsi
>> cdroms.

>> I'm using an Adaptec aha1542 scsi adapter with a toshiba cdrom
>> and a yamaha cdr.  Could the adapter be causing this error?
>> I'm running debian linux kernel 2.0.30 on a 486 w/ 24 megs of ram.

--
Bryan Armstrong

 
 
 

1. Running *really* low on DMA buffers

Has anyone ever seen the message:

Warning - running *really* low on DMA buffers
last message repeated 14 times

in his/her syslogs? This occured to me while copying some large files
from a UDMA EIDE harddisk to a scsi-emulated IDE Iomega ZIP-drive. I
don't seem to understand the kernels complaint; the harddisk can wait,
can't it? Or does the kernel make some kind of guess about the speed of
the writing media (in my case a zip drive) and tell the UDMA hd to start
dumping lange amounts of data in the DMA-buffers hoping the writing
media will be fast enough to clear the buffers in time?

Greetings, Pieter van Beek

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