[CentOS] 64bit vs 32bit

[nate]

Matt wrote:
> I am upgrading a server that mounts in a rack.  Its going on the
> cheapest socket 775 CPU I can buy and in a 1u rack case.  All its for
> is keeping some log files and doing some simple MYSQL/PHP database
> stuff.  Not a work horse at all.  Anyway, is it better to go 64bit or
> 32bit for the CentOS 5.x install?  I do not see needing huge amounts
> of RAM or anything like that on this box.  Would the 32bit version be
> more tried, proven and stable?

Stick to 32-bit unless there's an explicit need to go to 64-bit.
64-bit requires a lot more memory.

64-bit should be perfectly fine from a stability perspective but
it's too much of a memory hog.

Sample memory usage(32-bit):
root      4059  0.0  0.2 11616 4532 ?        S    04:02   0:01
/usr/sbin/snmpd -Lsd -Lf /dev/null -p /var/run/snmpd.pid -a
root     10721  0.0  0.0  4516 1048 ?        Ss   Jun23   0:00 /usr/sbin/sshd
postfix  20038  0.0  0.0  5560 1720 ?        S    09:49   0:00 pickup -l -t
fifo -u
root     22302  0.0  0.1  7488 2480 ?        Ss   11:21   0:00 sshd: root at pts/1
root     29154  0.0  0.0  6780 1692 ?        Ss   Jul30   0:01
/usr/libexec/postfix/master
postfix  29158  0.0  0.0  6024 1868 ?        S    Jul30   0:00 qmgr -l -t
fifo -u

64-bit:
root      2792  0.0  0.0 88028 5700 ?        S    04:02   0:02
/usr/sbin/snmpd -Lsd -Lf /dev/null -p /var/run/snmpd.pid -a
root     22946  0.0  0.0 26224 2108 ?        Ss   Jul30   0:00
/usr/libexec/postfix/master
postfix  22950  0.0  0.0 26336 2200 ?        S    Jul30   0:00 qmgr -l -t
fifo -u
root     26090  0.0  0.0 37100 2656 ?        Ss   11:23   0:00 sshd: root at pts/0
postfix  30228  0.0  0.0 26284 2104 ?        S    10:34   0:00 pickup -l -t
fifo -u
root     31734  0.0  0.0 21924 1180 ?        Ss   Jun23   0:00 /usr/sbin/sshd
---

snmpd - from 11M to 88M
postfix/master - from 6.7M to 26M
sshd - from 7.4M to 37M
postfix/pickup - from 5.5M to 26M

Unless you have gobs of ram and don't care about the extra memory
usage. For me unless I have processes that need more than 2GB
per process, or overall memory on the system is higher than 8GB
I stick to a 32-bit OS. If I have more than 8GB, that implies that
I actually plan to use more than 8GB at which point I believe 64-bit
starts making more sense as PAE can get pretty expensive for memory
intensive things. The above 64-bit system has 16G, the 32-bit
system above has 2G.

nate