I am trying to work out what the largest possible hard dirve my Centos 3.3 (RHEL 3 Clone) will detect.

I know the motherboard is limited to 137GB, but I remember reading some where that once linux has booted it does not need the bios to read or write to the hard drive. Thus getting around the Motherboard's 137GB barrier.

Can anyone verify this?

Thanks in advance.

Matthew

I've read the same thing. In my personal experience, I slaved a 160GB drive for extra storage to box with a bios limit of 137GB and linux saw the entire 160GB. The main limitation I've read about is if you intend to boot from the oversized drive. There you should create a partition within the bios size limits containing your /boot. As I understand it, once the kernel loads from /boot, linux kisses the bios and its hard drive size limits goodby.

Back in the '90s when this was much more of an issue (512MB limits, 2GB limits, etc.) I often worked around it using LILO boot parameters which bypassed the BIOS entirely. Since the MBR is always going to be within the first xxxMB/GB limitation you could look up older howtos and pass on the HDD geometry at the prompt, and then once the system is installed add the line to your lilo.conf file and re-install LILO to the MBR.

As far as the 137GB limit goes, specifically, look for BIOS hacks. On my Abit VP6, for example, there was a 137GB limit when I bought a 160GB drive so I was going to take a RAID controller I had on hand to run the drive, but decided that was overkill so I did some googling and found Paltrude's BIOS modes. There's a guy patching all kinds of BIOS images for various boards to overcome the 137GB limitation. I applied this BIOS image to my board and was able to see all 160GB of the drive - and I've since tried 250GB drives and was able to see the entire drives on those as well. There may very well be a BIOS hack for your board as well.

The limit has to do with the drivers, not the hardware. So in some cases the BIOS can only boot off the first part of a larger disk, that is how the /boot partition as hda1 came to be. Once the kernel is in memory the linux drivers are used and the drive can be almost any size. On a large drive the block number is sent in 2 pieces after a certain command is sent to it, meaning that the physical interface has not changed, just the way the driver sends the addressing commands.

So put your kernels into /boot (hda1, 128MB or something small like that) and use any size drive you like.

RT

Okay, if you want to play semantics, the BIOS is not hardware. From a practical perspective it is, and msjenkins' best solution would be to apply a BIOS update if there is one available.

Thanks for the help everyone.

I had a look for bios updates and found none that would fix the 137Gb limit.
I will buy a WD 200Gb hard drive and give that a whirl.



Edit: Spelling

What motherboard do you have?

Intel® Desktop Board D815EFV or D815EPFV.

http://support.intel.com/support/mot...sktop/d815efv/

Edit: Add link to intel website

I can't find any for that board either. Have you considered using a Promise ATA controller with native 48bit LBA support? The cards are under $40.

I will try the Hard drive first. If I don't get the full 200Gb I will probably get an ATA controller of some sort.

Thanks for your help once again.

The 200Gb Hard Drive was installed and worked like a charm.
It was mounted with mount -t ext3 /dev/hdb1 /home/share

The drive would need to be partitioned if I were to boot from this drive.

No add in cards were required.

Once again thanks for all of your help.

Cheers,


Matt

If you want to use hard drives reaching to 400 GB or more, you have to configure the kernel to support large devices. Each kernel version is different. You have to look closely at the kernel options to spot it. Right now it seems the option will give support for drives reaching to 2 TB which is big at this time, but it will soon change very, very soon.

Next time search this forum because there are several under this topic.