Re: MicroVAX 3100/20 is apocalyptically slow even with 32MB of RAM

[Daniel Seagraves <dseagrav%lunar-tokyo.net@localhost>]

> On Apr 17, 2026, at 4:03 PM, John Klos <john%klos.com@localhost> wrote:
> 
>> I have a MicroVAX 3100/20 with 32MB of RAM that once ran NetBSD many years ago. I recently had occasion to replace its disk and install 10.1, and it is superlatively slower than I remember it being. It?s so slow that it?s been trying to just bootstrap pkgsrc for about a week now, with pauses to allow the daily cron script to complete otherwise it won?t complete in less than 24 hours. The system time loses about 10-15 minutes a day, presumably because it can?t keep up with the clock interrupts. This is after I copied the GENERIC kernel config, stripped out all of the VAX models and devices that weren?t needed, and stripped out all of the RAM-based filesystems.
> 
> I have a VAXstation 4000/30 that has a defective CPU cache. Because of this, it benchmarks quite similarly to a 5 MHz 11/780, even though it runs at 25 MHz. I wonder if your cache isn't getting turned on correctly, or if your cache is failing...

I’ll have to look at the test results next time it powers up. I don’t think it flagged any hardware faults, and I’ve even replaced the nvram battery with a modern substitute.

>> I don?t think RAM is the issue because I haven?t seen it go above 12-14MB active in top. It uses more swap than it does RAM.
>> 
>> Is there something configuration-wise I should try, or is this model just too slow to be supported anymore?
> 
> Your machine should be at least half as fast as my fully working VAXstation VLC. I'm running NetBSD 11, and it really isn't any slower than NetBSD 9 or 10. Do you know what version of NetBSD you had on it many years ago?

I want to say NetBSD 4 or 5? Maybe earlier? It was around the time that SCSI DMA was fixed on the 3100s and we didn’t have to use PIO mode anymore.