That depends. All partitions with system files need to be mounted for the system to operate.
Drive/partition configuration is handled by the file /etc/fstab. Comment out any partition you wish not mounted.
# Managing drives
LNAG - Accessing my drives
Rute - Device Mounting
My file:
Code:
# Duron 950 uilleann Red Hat 7.3 /etc/fstab file
/dev/hda7 / reiserfs defaults 1 1
/dev/hda3 /boot ext3 defaults 1 2
none /dev/pts devpts gid=5,mode=620 0 0
/dev/hda9 /home reiserfs defaults 1 2
/dev/hda1 /mnt/win98 vfat defaults 0 0
/dev/hda2 /mnt/win2k ntfs defaults 0 0
none /proc proc defaults 0 0
none /dev/shm tmpfs defaults 0 0
/dev/hdb4 /pub ext3 defaults 1 2
/dev/hdb1 /pub/iso reiserfs defaults 1 2
/dev/hdb2 /pub/iso/LinuxDistros ext3 defaults 1 2
#/dev/hda6 /mnt/gentoo reiserfs defaults 1 2
#/dev/hda8 /mnt/mandrake ext3 defaults 1 2
/dev/hda5 swap swap defaults 0 0
/dev/cdrom /mnt/cdrom iso9660 noauto,owner,ro 0 0
/dev/fd0 /mnt/floppy auto noauto,owner 0 0