Re: [cobalt-developers] RAQ 4 Memory

[Gerald Waugh <gwaugh@xxxxxxxxxxxxxxxxxxxxxxx>]

On Tue, 1 Jul 2003, Gerald Waugh wrote:

> On Tue, 1 Jul 2003, Harald Kapper wrote:
> > the final answer from one of our customer's raq4-boxes:
>
> > [root /root]# free -m
>        total    used    free   shared  buffers  cached
> > Mem:  948      436    512     181     265       77
> > -/+ buffers/cache:     93     854
> > Swap: 128       0     128
>
> When you boot up a RaQ with 1GB RAM it will tell you that
> It can not use 1GB memory and limits it to something like
> 860MB. Odd number I know, and I think it is 1024KB for MB.
>
> Also, there may be a problem with 'tag' RAM. "cache tag RAM"
> on the motherboard keeps track of a number of pages
> (64M, 256M, 512M) If a page falls outside this boundary,
> it will be fetched from main memory, even if the processor
> or board had the page in the L1/L2 cache. This can make the
> system run slower than it would with less RAM.
>
> I am not sure what the 'tag ram' cache size is on the RaQ MB.
> But, it may be a problem. Only testing with an application
> written for testing this will determine actual results.
>
> Also there is high-density RAM and low-density RAM,
> high-density is usually less expensive, and RaQs do
> not run well on high-density RAM.
>
> Another observation is that we have seen some RaQs appear
> to run well on 1GB RAM, but during an OS restore, using
> big drives, the format md4 (hda4) [big-partition] the RaQ
> would hang while calculating the inodes (lots of inodes on
> big disk) entries.
> Changing the RAM back to 512MB would allow the restore
> to progress without incident.
>
> So will a RaQ3/4 run on 1GB of RAM?
> It appears to, but is all OK?
>

I wanted to add to this for the archives.
We have tested RaQ3s and RaQ4s with 768MB RAM
one 512MB and one 256MB. They run FINE,
went through a restore with 80GB drives,
and never had and error.

So, our recommendation is to use 768MB

Gerald
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