I have a PC with 4 harddisks and one ssd drive, presently PC boots from the 1st harddisk and other harddisks (sometimes 1, 2 or 3, depends upon the requirement) are used for the storage.
Now i want to boot the PC from SSD and use the other harddisks for the storage only.
My problem is that when system boots it takes 1st harddisk as sda and SSD as sdb, if i am using only one harddisk, and if i use 2 harddisk it takes sdc as SSD. So i am not able to give fix boot point in menu.lst file, if i wish to use root filesystem from SSD.
I am using 2.6.33.7 kernel and grub bootloader.
I have tried using initrd with udev but not able to include and start udev properly in initrd.
I am trying to boot from UUID or LABEL, but no success.
Am i missing something in kernel to get the UUID or LABEL.
Please suggest the solutions ?

Whats the uuid of the Ssd and what's the grub config

From this I get the impression that you remove disks from your configuration depending on your storage need?
Am I right?

If you remove disks, you will find that you change the definition of some of those left. (The sda, sdb, sdc definition)

With 4 disks I would assume (My first mistake! you shouldn't assume anything!) you have a couple of PATA controllers on board, both with a master/slave disk? Your fifth disk possibly a SATA connection? You need to let us know how they're connected.

Then... The boot device is usually set up in the BIOS (Sometimes it's just set as an adapter and the adapter's BIOS defines the boot device.) Too many things you haven't told us yet!
Grub also uses the sda, sdb, sdc definitions to boot the required image so if you remove a drive, it may well find the wrong image.

Can you clarify exactly what you're doing so I don't have to assume anything 'cos my head hurts.

Play Bonny!

i have all SATA drives and ssd is also at scsi bus. All of them are on the same scsi bus. BIOS is enabled with the "boot from USB first". In ssd drive i have linux kernel and initrd image.
Grub is not able to find the drive, from where it has to boot as the no. of hard drives are dynamic. Thats why i want to give grub some fix information using UUID or LABEL, but not able to do the same.

I'm sorry I don't understand...

SATA drives use a different protocall from SCSI ones. SATA drives are connected serially, one drive per connector, each has it's own controller Motherboards usually have two PATA connectors; a master and slave drive per connector - can handle 4 parallel ATA drives in total.

Serial SCSI is known as SAS (Serial Attached SCSI) and again, each drive would have a separate connector. SATA and SAS are not the same!
Neither SATA nor SCSI are USB devices - this is yet another protocol though the underlying disks are probably PATA or SATA. It'd depend on the internal disk to USB conversion.

What is the bootlist you have set up in the BIOS? Your first device is USB, I'd assume the second is CD/DVD, what is the first hard drive? Which drive is your SSD? What order are your hard disks in?

Again, are you removing disks and expecting the definitions to remain the same? You didn't answer my question in #3 above.

Play Bonny!

thanks for the reply.

I am using intel's DH55HC motherboard, which provides 6 SATA connectors out of those 4 SATA

connectors are used by me for the hard drives. It also provides 12 USB 2.0 ports (EHCI

compatible), out of which one supports USB Solid State Drive (SSD), through which my ssd

drive is connected.

OK, I've checked out your motherboard spec and understand where you're comming from.
However, I'm unaware of any computer which can handle auto booting when the number of disks it has attached can change between boots. Maybe that's me though.

Can you get to a boot menu while the system is POSTing? Possibly by pressing <esc> somewhere within the process? If so, what do you get if you select USB with the SSD plugged in? I've got a wee 128Mb USB drive with Puppy Linux on it which I can use for rescuing systems by booting from it directly. Maybe this would be the way to go in your situation? Booting from an individual SATA drive may be more complicated.

Maybe if Grub was installed on the SSD rather than elsewhere... Hmm...Your USB disk would have to be permanently attached I reckon as you'd lose all dual boot info if it was missing.

Play Bonny!