Hello i have a redhat box, after re-installing the os on /dev/hda i lost the access the partitions of the other two discs (/dev/hd3 /dev/hdg). What is the safest thing to do in this situation?
Any help will be appreciated.

PS: this is an extract of dmesg

Linux version 2.4.20-31.9 (bhcompile@porky.devel.redhat.com) (gcc version 3.2.2 20030222 (Red Hat Linux 3.2.2-5)) #1 Tue Apr 13 17:41:45
...
Kernel command line: ro root=LABEL=/ linear
...
CPU: Trace cache: 12K uops, L1 D cache: 8K
CPU: L2 cache: 512K
...
Uniform Multi-Platform E-IDE driver Revision: 7.00beta3-.2.4
ide: Assuming 33MHz system bus speed for PIO modes; override with idebus=xx
ICH3: IDE controller at PCI slot 00:1f.1
PCI: Enabling device 00:1f.1 (0005 -> 0007)
PCI: Found IRQ 11 for device 00:1f.1
ICH3: chipset revision 2
ICH3: not 100% native mode: will probe irqs later
ide0: BM-DMA at 0x2060-0x2067, BIOS settings: hdaio, hdbio
ide1: BM-DMA at 0x2068-0x206f, BIOS settings: hdcio, hddio
HPT370: IDE controller at PCI slot 04:02.0
PCI: Found IRQ 11 for device 04:02.0
PCI: Sharing IRQ 11 with 00:1f.3
HPT370: chipset revision 3
HPT370: not 100% native mode: will probe irqs later
HPT37X: using 33MHz PCI clock
ide2: BM-DMA at 0x4000-0x4007, BIOS settings: hdeMA, hdfio
ide3: BM-DMA at 0x4008-0x400f, BIOS settings: hdgMA, hdhio
hda: Maxtor 6Y120L0, ATA DISK drive
hdb: HL-DT-STDVD-ROM GDR8161B, ATAPI CD/DVD-ROM drive
blk: queue c03972e0, I/O limit 4095Mb (mask 0xffffffff)
hde: Maxtor 6Y200P0, ATA DISK drive
blk: queue c0397ba8, I/O limit 4095Mb (mask 0xffffffff)
hdg: Maxtor 6Y200P0, ATA DISK drive
blk: queue c039800c, I/O limit 4095Mb (mask 0xffffffff)
ide0 at 0x1f0-0x1f7,0x3f6 on irq 14
ide2 at 0x48d0-0x48d7,0x48c6 on irq 11
ide3 at 0x48c8-0x48cf,0x48c2 on irq 11
hda: attached ide-disk driver.
hda: host protected area => 1
hda: 240121728 sectors (122942 MB) w/2048KiB Cache, CHS=14946/255/63, UDMA(100)
hde: attached ide-disk driver.
hde: host protected area => 1
hde: 398297088 sectors (203928 MB) w/7936KiB Cache, CHS=24792/255/63, UDMA(100)
hdg: attached ide-disk driver.
hdg: host protected area => 1
hdg: 398297088 sectors (203928 MB) w/7936KiB Cache, CHS=24792/255/63, UDMA(100)
ide-floppy driver 0.99.newide
Partition check:
hda: hda1 hda2 hda3 hda4 < hda5 >
hde:
hdg:
ide-floppy driver 0.99.newide
md: md driver 0.90.0 MAX_MD_DEVS=256, MD_SB_DISKS=27
md: Autodetecting RAID arrays.
md: autorun ...
md: ... autorun DONE.
....
VFS: Mounted root (ext2 filesystem).
Journalled Block Device driver loaded
kjournald starting. Commit interval 5 seconds
EXT3-fs: mounted filesystem with ordered data mode.
Freeing unused kernel memory: 112k freed
...
EXT3 FS 2.4-0.9.19, 19 August 2002 on ide0(3,1), internal journal
Adding Swap: 3068404k swap-space (priority -1)
kjournald starting. Commit interval 5 seconds
EXT3 FS 2.4-0.9.19, 19 August 2002 on ide0(3,2), internal journal
EXT3-fs: mounted filesystem with ordered data mode.
kjournald starting. Commit interval 5 seconds
EXT3 FS 2.4-0.9.19, 19 August 2002 on ide0(3,5), internal journal
EXT3-fs: mounted filesystem with ordered data mode.
ohci1394: $Rev: 693 $ Ben Collins <bcollins@debian.org>
PCI: Found IRQ 11 for device 04:01.0
PCI: Sharing IRQ 11 with 00:1d.0
ohci1394_0: OHCI-1394 1.0 (PCI): IRQ=[11] MMIO=[fc302000-fc3027ff] Max Packet=[2048]
ieee1394: SelfID completion called outside of bus reset!
ieee1394: Host added: Node[00:1023] GUID[001106000000f5d0] [Linux OHCI-1394]

Create a mount point for each then try mounting them from the command line. Once you have verified that this works, create entries in your /etc/fstab file so that they are automatically mounted on bootup.

For example:
mkdir /data1
mount /dev/hde /data1
mkdir /data2
mount /dev/hdg /data2

It mounts the disk at boot time, but still doesn't see the partitions. Is this ok?

Your answer is confusing, but then so was my response. ;-)

My suggestion to mount the disks manually was hastily typed. You need to specify the partition you want mounted, not just the disk. Assuming that your partitions of interest are the first partition on the disk, the mount commands should have looked like:

mount /dev/hde1 /data1
mount /dev/hdg1 /data2

I don't know what you meant by being able to mount the disks, but not see the partitions.