p4 PATA boot question

[lakedude]

We have an old computer with 2 hard drives on one cable in a master slave combo. The bios "sees" both drives and both drives are accessible however it seems only the master is bootable. The slave has a bootable partition that will boot if it is the only drive in the system but it does not seem to want to boot with the other drive in the system. Does that sound right? The bios displays both hard drives but only one hard drive option is given in the boot order section.

 

[deustroop]

We have an old computer with 2 hard drives on one cable in a master slave combo. The bios "sees" both drives and both drives are accessible however it seems only the master is bootable. The slave has a bootable partition that will boot if it is the only drive in the system but it does not seem to want to boot with the other drive in the system. Does that sound right? The bios displays both hard drives but only one hard drive option is given in the boot order section.

That's correct.
See https://en.wikipedia.org/wiki/Parallel_ATA#Multiple_devices_on_a_cable

" Also, depending on the hardware and software available, a single drive on a cable will often work reliably even though configured as the slave drive (most often seen where an optical drive is the only device on the secondary ATA interface)."

 

[TheELF]

Jup,depends a lot on the bios, if there is no boot order or disk order that you can change you can only boot from the first drive,you can install a bootmanager on there though if you need to change boot drives often.

 

[sm625]

This brings back nightmare memories of trying to swap the master and slave without taking the drives out. This led to some pretty ugly cable contortions... And then there were the jumpers on the drives.... I tried to avoid this whenever possible, by only placing one drive on each cable. Luckily there werent too many boards where you only had one IDE connector on the motherboard and no SATA.

 

[Paperdoc]

There's a solution, but it involves changing cable connections and maybe physically moving drive units, as sm625 has hinted.

You have two HDD's sharing one PATA port and cable on a mobo. Perfectly normal. However, the mobo BIOS is of such an old style that it only allows for booting from the Master device on that PATA port. Now, you know that the Slave HDD CAN boot, but only when it is the only HDD on the cable. So your solution is to swap drive units - that is, convert the current Slave unit to be the Master, and current Master to Slave. Then the one HDD that HAS a bootable OS on it will be the port Master device and it will work.

There are two (Maybe three) steps to do this.
1. Change the jumper settings on each HDD unit. In each case, use the jumper diagram on that unit - do not assume the diagram on one unit is the same as the settings for the second unit. Take the current one set as a Master and set it to be a Slave. Take the current Slave unit and set it to be the Master - or, if this is a different option, to be a Master with Slave Present.
2. You must re-connect the wide data cable ribbon differently. The END connector (usually Black) MUST go into the HDD that is now the Master, and the middle connector (usually Grey) must go to the Slave.
3. Getting those ribbon cables into the correct HDD units may be tricky, depending on cable lengths, etc. So you MIGHT have to remove the two HDD units physically and re-install them in the opposite slots, just to get Master and Slave units in convenient locations for cable attachment.

 

[edcoolio]

We have an old computer with 2 hard drives on one cable in a master slave combo. The bios "sees" both drives and both drives are accessible however it seems only the master is bootable. The slave has a bootable partition that will boot if it is the only drive in the system but it does not seem to want to boot with the other drive in the system. Does that sound right? The bios displays both hard drives but only one hard drive option is given in the boot order section.

That is correct. The master will be the only bootable drive in this configuration.

I will assume that the setting is not 'cable select' to identify the master/slave configuration, but rather that it is defined by jumpers directly on the drive. I will also assume you want a way to change this out on a whim. Linux distro hopper maybe? Anyways...

Probably the easiest solution on these old systems to swap master/slave is to buy two external trays. They will look like hot-swappable trays, but obviously, they will not be. Basically, you can throw your drives into them (after installing and connecting) and whenever you want to change master/slave config, just turn off your box. Eject the drives and change the jumpers on the hard drive(s) to whatever you want.