[CentOS] CentOS 4.4 not seeing all RAM

Kanwar Ranbir Sandhu m3freak at thesandhufamily.ca
Mon Mar 5 16:46:35 UTC 2007


Hi Everyone,

My server is only seeing 4.8 GB out of 6 GB available.  I don't know
why.

I have a CentOS 4.4 x86_64 server running on a Tyan s2895 with 6 GB of
RAM (two 1 GB sticks and 2 2 GB sticks).  I upgraded the RAM, powered up
the server, and when CentOS was finished booting, checked the available
RAM with free.   This is what it's reporting:

                 total           used            free     shared
buffers     cached
Mem:       4809064    4769492      39572          0     197156
3127704
-/+ buffers/cache:    1444632    3364432
Swap:      2064376        176    2064200

The BIOS sees all of the RAM.  In fact, it looks to me like the kernel
knows 6 GB is available.  But, it is only using 4.8 GB because I see
this in dmesg:

Memory: 4808464k/6291456k available (2106k kernel code, 0k reserved,
1299k data, 196k init)

What happened to the other 1 GB+ of RAM?

BTW, the server isn't running all the newest updates, but it is running
the latest CentOS 4 kernel (2.6.9-42.0.10.ELsmp).

Regards,

Ranbir
-- 
Kanwar Ranbir Sandhu
Linux 2.6.19-1.2911.fc6 i686 GNU/Linux 
11:39:08 up 2 days, 10:28, 2 users, load average: 1.18, 0.64, 0.60 





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