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From: bill@franklin.com (Bill)
Newsgroups: comp.unix.admin,comp.unix.internals
Subject: Same device, two mount points? Or, overutilizing my RAM disk...
Message-ID: <900908.7074@franklin.com>
Date: 8 Sep 90 07:49:40 GMT
Organization: Franklin Electronic Publishers
Lines: 38

Hi,

I have a question, or rather several. I just recently wrote myself
a RAM disk driver for my system for use with /tmp. (Why do I want
a RAM disk? After much tuning, I find that my system, a SysV3.0,
spends most of its time under load doing disk related stuff. I
have cycles and memory to spare, however.) There are (at least)
two defects with this.

The first is that /tmp is not the only directory that I'd like to
put into the RAM disk; I'd also like to put in /usr/tmp and maybe
/usr/spool/locks and I'm sure I could find a few others that
could be usefully made to go there. Well, the only solution I
could think of (remember, this is SysV, no symbolic links), is to
create several device files, each pointing to the same RAM disk
and to mount each separately. (No, I don't want several RAM
disks!)

If I do this, there are obviously some utilities that will get a
bit confused, e.g., find would scan the directories more than
once, but is there anything that will outright break? I can't
think of anything, but I'm only a guru-in-training. :-)

The second is that a fixed RAM disk is really brainless. There's
all that memory off on its own, not usable for anything else. I'd
really like to be able to integrate the RAM disk with the block
buffering system, so that the RAM disk would have its allocated
blocks come out of the pool.

Does anyone know of any reason why that could not be made to work?
Or even if someone has done something like that?

For my final question: The whole purpose of the RAM disk is to
better utilize my system. I have scads of memory, a reasonably
fast CPU, slow disks :-(, and SysV3.0 :-(. I'm not rich enough to
change either of those negatives by applying money, so I have to
get around them another way. Does anyone have any other
suggestions on eliminating the disk bottleneck?