I want to determine and increase ram size on RHEL 4.

Can anyone help me with this?

I need 96MB, so I used a bs of 1024 and count of 93750 for the dd command. It failed.

FAILS (RHEL 4)
==============
dd if=/dev/zero of=/dev/ram1 bs=1024 count=93750
dd: writing `/dev/ram1': No space left on device
16385+0 records in
16384+0 records out

dd if=/dev/zero of=/dev/ram1 bs=1024 count=16385
dd: writing `/dev/ram1': No space left on device
16385+0 records in
16384+0 records out

Count of 16384 works, but nothing higher does.

WORKS (RHEL 4)
==============
dd if=/dev/zero of=/dev/ram1 bs=1024 count=16384
16384+0 records in
16384+0 records out

dd if=/dev/zero of=/dev/ram2 bs=1024 count=16384
16384+0 records in
16384+0 records out

$ cat /proc/meminfo
MemTotal: 16574352 kB
MemFree: 14907316 kB
Buffers: 253092 kB
Cached: 729308 kB
SwapCached: 140 kB
Active: 865416 kB
Inactive: 272900 kB
HighTotal: 15794176 kB
HighFree: 14891264 kB
LowTotal: 780176 kB
LowFree: 16052 kB
SwapTotal: 20414456 kB
SwapFree: 20414316 kB
Dirty: 8 kB
Writeback: 0 kB
Mapped: 195864 kB
Slab: 496572 kB
CommitLimit: 28701632 kB
Committed_AS: 447724 kB
PageTables: 5084 kB
VmallocTotal: 106488 kB
VmallocUsed: 12016 kB
VmallocChunk: 94152 kB
HugePages_Total: 0
HugePages_Free: 0
Hugepagesize: 2048 kB
$ free
total used free shared buffers cached
Mem: 16574352 1667100 14907252 0 253092 729308
-/+ buffers/cache: 684700 15889652
Swap: 20414456 140 20414316

I have a machine with a Debian distribution on which the dd command with bs=1024 count=93750:

DEBIAN:
dd if=/dev/zero of=/dev/ram1 bs=1024 count=93750
93750+0 records in
93750+0 records out


$ cat /proc/meminfo
total: used: free: shared: buffers: cached:
Mem: 1585790976 1579163648 6627328 0 33210368 1361088512
Swap: 1073733632 14704640 1059028992
MemTotal: 1548624 kB
MemFree: 6472 kB
MemShared: 0 kB
Buffers: 32432 kB
Cached: 1327956 kB
SwapCached: 1232 kB
Active: 938112 kB
Inactive: 428852 kB
HighTotal: 1048576 kB
HighFree: 2860 kB
LowTotal: 500048 kB
LowFree: 3612 kB
SwapTotal: 1048568 kB
SwapFree: 1034208 kB
$ free
total used free shared buffers cached
Mem: 1548624 1542228 6396 0 32432 1328008
-/+ buffers/cache: 181788 1366836
Swap: 1048568 14360 1034208


Thanks!

Nothing (directly) to do with installed RAM - defined in the kernel config; simple grep for "ram" will show the current specification.
Can be over-ridden on boot - see ramdisk.txt in the Documentation directory of your kernel source tree.