hkclark@xxxxxxxxx wrote:
On 2/8/07, Johnny Hughes <mailing-lists@xxxxxxxxxxxx> wrote:
It should not be a problem as lots of your memory used is buffers and
cache.
CentOS-3 is going to be supported for a while yet (EOL is scheduled for
Oct 31, 2010), so if it is working perfectly and doing what they want,
they may want to keep it though.
If they upgrade or don't, the memory should be OK either way .
Hi Johnny,
Good info -- thanks. They have a small app they want to add that
requires a newer version of Perl than 5.8.0 that comes with CentOS 3.
Rather than getting into a non-RPM version of Perl, we were thinking
going to CentOS 4 would be easier and cleaner.
In your experience, would you say that my "quick & dirty" measurement
of CentOS 4 needing 10-25 MB more memory than CentOS 3 (again, for a
non-X box with a minimal install) is accurate (at least in approximate
terms)? Or is there something I'm not taking into account -- e.g,
some of the libraries and/or other "basic server apps" such as apache
with PHP or MySQL will make that number much higher? Although this
box is doing OK on memory now, I would hate to kill their possible
expansion plans just because we did an upgrade and it sucked up way
more memory than we though.
Again, thanks for all the great things you and the CentOS team are doing!
Here is the output of "free" for 2 identical systems that happen to be
running CentOS3 and CentOS4. The only difference is the CentOS4 system
has 2GB RAM vs 1GB in the CentOS3 system.
The CentOS3 system shows:
total used free shared buffers cached
Mem: 1024292 660572 363720 0 102612 397072
-/+ buffers/cache: 160888 863404
Swap: 2104464 0 2104464
CentOS4 shows:
total used free shared buffers cached
Mem: 2074928 2030412 44516 0 276628 1365792
-/+ buffers/cache: 387992 1686936
Swap: 2104464 144 2104320
As others have noted, a lot of the free RAM is just gobbled up as
buffers and cache. As needed, the system will reallocate that memory so
that your fancy perl application can get at it. :)
Call me crazy, but I don't understand the agonizing fork in the decision
tree here. RAM is ridiculously cheap. Why not just upgrade to 1GB
while you're doing the 3-->4 upgrade? I suspect it isn't really needed,
but it will add minimal cost to the operation (certainly much less than
the cost of your time to accomplish the software update and test the new
system).
Cheers,
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