I am working on a Tyan 2466 SMP/Athlon server now and am getting tons of
reiserf errors (see attached /var/log/syslog) that claim an i/o error, yet
the log does not show any errors from the driver (should it?).
Unfortunately, Reiser does not indicate which drive the error is produced
from. My configuration is:
Tyan 2466 SMP 2 x AMD2400-MP
512 MB PC2100 DDR-> not registered!
Debian woody
2.4.21 reiser
system drive (os, swap) wd800-bb (80 gb ide)
data drives: 3ware 7200, 2 x wd2000 (200 gb ide) RAID-0
On Wednesday 25 June 2003 07:17 pm, Edward Tandi wrote:
> On Wed, 2003-06-25 at 23:59, Timothy Miller wrote:
> > Edward Tandi wrote:
> > > Yes, for SMP mode you absolutely need to use 'registered' RAM. Normal
> > > PC2100 ram will work OK with one processor but quickly fails with two
> > > (I had the same problems). Apparently, DDR RAM uses one clock edge to
> > > transfer in one direction and the opposite edge to transfer back again
> > > so the registers do synchronisation between one processor writing to
> > > the same location that the other one reads from. That's how it was
> > > explained to me anyway.
> >
> > DDR memory works very much like single data rate, except that data is
> > transferred (in whichever direction it's going) on both edges of the
> > clock, thus doubling the transfer rate. The memory does not switch
> > between reading and writing as you describe it.
> >
> > I believe registering is for reliability. Data is transferred one clock
> > cycle later but reduces signal loading.
>
> Thanks for the clarification. I do not profess to be an expert in the
> technology. Two writes or a read+write per clock cycle is close enough
> for the purpose of the discussion.
>
> The point I was trying to make is that the registers are there to deal
> with an SMP race condition of some sort. Athlon MP motherboards fitted
> with two processors will not work properly without 'registered' RAM. I
> have hard experience of this and it this experience I am sharing with
> someone who is seeing the same symptoms.
>
> Ed-T.
-- Joe Briggs Briggs Media Systems 105 Burnsen Ave. Manchester NH 01304 USA TEL 603-232-3115 FAX 603-625-5809 MOBILE 603-493-2386 www.briggsmedia.com
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