Hallo swapers,
thank you for all those quick responses. As usual, the answer to my
question is far more than twofold, so i've to try a summary.
original question:
>is it really necessary to add 3GB of swap space to a machine, which has
>1GB of RAM?
solutions:
many of you statet, that the amount of swapspace totaly depends on the
application you're running. So if you are about running something like
SAP or a database, 2x-3x of swap would be the best choice. If you're
planning C or Fortran development server, then 256-512 MB should be
sufficent (this advise come from digital support).
Over all, reserving enough swapspace, i.e. twice the amount of RAM
minimum, is recommended, unless you are willing to caculate the amount
of swap in detail. Bill Body gave very nice hints about that topic (is
this really your name ;-)
> Swap space must be large enough to hold the sum of all shared memory,
> shared libraries, stack, and data for the largest
> executable process.
> The size command is a useful tool for acquiring information on process
> size:
> # size /usr/bin/vi
> text data bss dec
> hex
> 262144 32768 348736 643648 9d240
> Size returns the code (text), data and bss (data uninitialised at the
> beginning of process execution) for a program.
> Since no swap space is reserved for code ( the first figure ) , you
> would combine only the second and third sizes to estimate the size a
> program occupies in the swap area. Multiply the figure by the number of
> users executing the program at the systems busiest time , since each
> user is allocated data and bss.
> Repeat this calculation for each program executed when the system is at
> its busiest.
> Shared memory must also be calculated in your swap-space needs
> assessment. To display the amount of shared memory your system is using
> at any given moment use the icps -b command. You need to add up the>
> SEGSZ column.
Another group of swappers mentioned to use lazy-swapping rather than
eager mode to save disk space.
mit freundlichen Gruessen
Reimund Willig
------------------------------------------
e-mail: willig.reimund_at_gdr.de
tel: +49-5205-941747
fax: +49-5205-941725
** Schwer ist leicht was **
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Received on Thu Aug 13 1998 - 14:12:51 NZST