Tru64 and memory expansion
H Vlems
384 MB main memory. I bought 1 GB on eBay recently for this system.
Will Tru64 automatically recognize the additional memory or do I need
to change configuration files (beforehand)? I'm familiar with VMS but
not experienced with Tru64, so an elaborate answer is appreciated :-)
Hans Vlems
Michael Kraemer
> I run Tru64 V5.0 on an Alphaserver 800. The system is configured with
> 384 MB main memory. I bought 1 GB on eBay recently for this system.
> Will Tru64 automatically recognize the additional memory
yes, usually.
Except in case the RAM does not quite fit the specs for the target machine.
I've seen console recognizing such memory,
but on boot Tru64 crashed.
> or do I need
> to change configuration files (beforehand)?
Not that I know of.
At least that's how it worked with workstations.
> I'm familiar with VMS but
> not experienced with Tru64, so an elaborate answer is appreciated :-)
not necessary.
Dennis Grevenstein
You might want to check if you have enough swap space.
Tru64 offers two modes of swapping. The default behaviour is
that it always reserves swap space whenever you need virtual
memory, so the amount of virtual memory available is is the
amount of swap space available.
The second mode doesn't reserve swap space, so you can have
as much virtual memory as you have swap + real memory.
There are reasons for having one or the other.
Anyway, if you can't or don't want to increase swap space,
if you don't have enough swap for 1GB of RAM, you can delete
/sbin/swapdefault (and reboot) to enable the lazy swap
mode.
Dennis
--
Don't suffer from insanity...
Enjoy every minute of it.
H Vlems
wrote:
Dennis, I understand the point you're making. Is there a command that
shows what swap
mode my system uses?
Hans
R.A.Omond
Hans, this is from the "man swapon" page for a Tru64 V5.1 system.
The method was different for Tru64 V4 (that was what Dennis was
suggesting above). I can't remember which method was used in Tru64
V5.0. And, oh by the way, if your workload stays the same, you're
much *less* likely to use the swapspace with the extra memory.
---
There are two strategies for swap space allocation: immediate mode and
deferred or over-commitment mode. The two strategies differ in the
point in time at which swap space is allocated. If immediate mode is
used, swap space is allocated when modifiable virtual address space is
created. If deferred mode is used, swap space is not allocated until
the system needs to write a modified virtual page to swap space.
Immediate mode is the default swap space allocation strategy.
Immediate mode is more conservative than deferred mode because each
modifiable virtual page is assigned a page of swap space when it is
created. If you use the immediate mode of swap space allocation, you
must allocate a swap space that is at least as large as the total amount
of modifiable virtual address space that will be created on your system.
Immediate mode requires significantly more swap space than deferred
mode because it guarantees that there will be enough swap space if every
modifiable virtual page is modified.
If you use the deferred mode of swap space allocation, you must estimate
the total amount of virtual address space that will be both created and
modified, and compare that total amount with the size of your system's
physical memory. If this total amount is greater than the size of
physical memory, the swap space must be large enough to hold the
modified virtual pages that do not fit into your physical memory. If
your system's workload is complex and you are unable to estimate the
appropriate amount of swap space by using this mode, you should first
use the default amount of swap space and adjust the swap space as needed.
To determine which swap space allocation mode is being used, check the
setting of the vm-swap-eager attribute in /etc/sysconfigtab. If this
value is either not specified or set to 1, the system uses immediate
swap mode. If it is set to 0 (zero), the system uses deferred mode.
H Vlems
> H Vlems wrote:
> > On 4 dec, 01:52, Dennis Grevenstein <dennis.grevenst...@gmail.com>
> > wrote:
> >> H Vlems <hvl...@freenet.de> wrote:
> >>> I run Tru64 V5.0 on an Alphaserver 800. The system is configured
> >>> with 384 MB main memory. I bought 1 GB on eBay recently for this
> >>> system. Will Tru64 automatically recognize the additional memory
> >>> or do I need to change configuration files (beforehand)? I'm
> >>> familiar with VMS but not experienced with Tru64, so an elaborate
> >>> answer is appreciated :-)
[snip]
> use the default amount of swap space and adjust the swap space as needed.
>
> To determine which swap space allocation mode is being used, check the
> setting of the vm-swap-eager attribute in /etc/sysconfigtab. If this
> value is either not specified or set to 1, the system uses immediate
> swap mode. If it is set to 0 (zero), the system uses deferred mode.
Thanks, that's a good explanation. Is this a Tru64 specific way of
paging/swapping or do all unixes
implement two methods?
Michael Kraemer
These details will certainly vary from one Unix to the other.
Tru64 for instance still uses the old-fashioned a/b/g partition
scheme (for boot/swap/all_the_rest),
with the AdvFS put on top of that. I'm almost sure
you can't easily change the size of a partition once it's
created. You can, however, change filesets defined on top
of a partition (e.g. /usr, /var, /opt defined on top of 'g').
Other Unices handle that differently.
My "home Unix", AIX, for example gives much more flexibility.
One can change all "logical volumes", including swap space,
any time later, in full run.
However, for hobbyist/workstation use I would not worry too much,
just accept what the installation procedure suggests.
Of course one might find it useful to define a large 'g' partition,
if one intends to store a lot of additional local software.
H Vlems
That was most interesting Michael, thank you. I haven't used AIX since
1998 or so
but I did remember that its filesystem was quite flexible and easy to
redistribute
diskspace across partitions without the need to reinstall.
IIRC AIX was (still is?) managed thru an operator interface (smit,
right?) which allowed
people to manage the system quite well even when not familiar with
AIX.
Hans
Michael Kraemer
> On 5 dec, 11:36, Michael Kraemer <M.Krae...@gsi.de> wrote:
>
>
> That was most interesting Michael, thank you. I haven't used AIX since
> 1998 or so
> but I did remember that its filesystem was quite flexible and easy to
> redistribute
> diskspace across partitions without the need to reinstall.
yes, saved me many hours of work time.
> IIRC AIX was (still is?) managed thru an operator interface (smit,
> right?)
yes. smit is the X-interface, smitty is for text consoles.
> which allowed
> people to manage the system quite well even when not familiar with
> AIX.
yes, that was the idea back then when IBM introduced AIX, in 1990.