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G5 Boots to Wrong Hard Drive

uller6

uller6

macrumors 65816
Original poster
May 14, 2010
1,126
1,910
I have a powermac G5, dual 2.0 GHz, 5 Gb ram, late 2003 model running 10.5.8 (client) as a headless file server in my closet. It's loaded with 2 x 1 Tb hard drives for storage, 1 x 640 Gb as a boot drive, and 1x 500 Gb as a backup to the boot drive (boot drive cloned every night with carbon copy cloner). The boot drive and the main data drive are both on the internal SATA bus in the original drive bays, and the 500 Gb and 1T backup drives are attached to a Seritek 1s2 SATA card. In system preferences, I set my boot drive to be the 640 Gb drive.

When I power the system off and power on again, the machine will restart into the 500 Gb backup drive - NOT the 640 Gb boot drive I specify. The only way I can convince the machine to boot into the 640 Gb boot drive is to go to system preferences, select the startup drive (which is already selected to the correct drive by the way), and then hit the restart button on the preferences tab.

I have already reset the SMC and PMU for this machine, and have rotated the hard drives among different drive bays and SATA connections. This strange behavior is driving me crazy. Has anyone seen this specific behavior before? Does anyone have any suggestions?
 
When the OS starts up, if it has no idea which drive to boot from, it sequences through them until it finds its first bootable drive.Odds are you use system preferences to set the drive up, but once it's powered down or rebooted, the information is lost. This implies that the small backup battery on the logic board needs replacement because the NVRAM settings are not being retained.

NVRAM for PPC and PRAM for Intel hold the ID of the device to boot from, among other things. Do a search for "NVRAM reset" and an Apple document should show up telling you how to do it (which I suspect you already know) but more importantly it might point you to other links that have specific battery information for your unit.

Here's a link to the Apple NVRAM/PRAM reset instructions:

http://support.apple.com/kb/HT1379
 
Last edited:
ZVH said:
When the OS starts up, if it has no idea which drive to boot from, it sequences through them until it finds its first bootable drive.Odds are you use system preferences to set the drive up, but once it's powered down or rebooted, the information is lost. This implies that the small backup battery on the logic board needs replacement because the NVRAM settings are not being retained.

NVRAM for PPC and PRAM for Intel hold the ID of the device to boot from, among other things. Do a search for "NVRAM reset" and an Apple document should show up telling you how to do it (which I suspect you already know) but more importantly it might point you to other links that have specific battery information for your unit.

Here's a link to the Apple NVRAM/PRAM reset instructions:

http://support.apple.com/kb/HT1379
Click to expand...

With a dead PRAM battery the NVRAM, where the boot device is stored, does stay when the machine is powered down. Only the clock is reset. OpenFirmware will only go through all drives on a system looking for a bootable one only if the set drive is no longer there or is no longer bootable. It will not start going through the drives looking for one without a cause as you're implying. On my own G5 the PRAM battery was dead for a month, but it always remembered to start from the correct drive out of the five it could.

The PRAM is powered by the battery and holds things like the date, time, current screen settings, ram disk information, and volume settings. It does not contain the current selected boot drive, that is kept in the NVRAM along with OpenFirmware settings. NVRAM does not require power to keep its contents intact. Both PowerPC and Intell Macs have PRAM and NVRAM.
 
Intell:

Thank you for the post.

First, I made a mistake when I stated "NVRAM for PPC and PRAM for Intel," it should, according to Apple's documents, be the other way around, which just raises more questions. If you look at the following link and click on the "more" link, it expands and states:

"On Intel-based Macs, this is stored in memory known as NVRAM; on PowerPC-based Macs, this is stored in memory known as PRAM."

Here's the link to that article:

http://support.apple.com/kb/HT1895#

Please note that most newer Intel based Mac's use EFI, whereas the older systems use Open Firmware. Apples clarification as to what the differences between NVRAM and PRAM appears to me to be sketchy and confusing. Note this quote from the link above:

"You may need to reset the NVRAM or PRAM if you experience issues related to these functions. For example, if your Mac starts up from a startup disk other than the one you've specified in Startup Disk preferences, or if a "question mark" icon appears briefly when your Mac starts up, resetting NVRAM or PRAM may help."

To add to the confusion, check out this link:

http://support.apple.com/kb/HT1379

If you go to the lower section of the page it identifies the "Contents of PRAM" and identifies "Startup disk" as one of the items identified in PRAM. Previously, in the same article it states,

"Important: If your computer does not retain parameter RAM (PRAM) settings when it is turned off, this generally indicates that the battery needs to be changed. Refer to Macintosh Family: Batteries and Part Numbers."

Interestingly, another article that was posted on CNET says the PRAM **IS** NVRAM. Here's a link:

http://reviews.cnet.com/8301-13727_7-10330118-263.html

I'm going to hazard a guess here (and that's what it is, a guess, not fact). NVRAM is used in PPC systems via open firmware to assign, among other things, a default boot drive - not THE boot drive, a default boot drive. On Intel systems, EFI uses NVRAM to do essentially the same thing, but the boot.efi on the default boot drive may, **may** redirect it to use another drive instead. This would make the use of PRAM unneeded on some Intel systems, yet I know for a fact that my late 2006 iMac does indeed have a PRAM battery. Regardless, parameters on both types of systems are read after NVRAM has been accessed and can override the default boot drive.

Does this make sense to you? Any input from you or anyone else knowledgable on this topic would be appreciated because I'd like to know.

Thanks for your response.
 
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PowerPC Macs have had NVRAM since they came out in 1994. All Macs have PRAM, even the first one back in 1984. In the Apple article you linked to it is saying what things is kept where. Not that one architecture does or does not have. EFI and OpenFirmware look at the NVRAM to see where they should load the kernel from and what options they should use when starting the kernel. That's really the only interaction they have with it besides resetting it. Both get the values for the default screen resolution and how loud they should play the startup chime from the PRAM.
 
Thanks for the responses both of you. Resetting the NVRAM/PRAM doesn't seem to help the problem, so I'll try replacing the motherboard battery. I'm not sure if this will fix however, as the date/time are always OK after a restart, but it can't hurt to try.
 
alt key

For a temporary solution hold down the alt/option key when booting and select the correct drive.
 
Jumpers?

I have no idea of this would apply to you, so please correct me if I am wrong, but could it be the jumpers on the drive?
I think that maybe you might have set the drive jumpers to "Slave" on the 640 and perhaps "Master" on the 500.
This is just an educated guess, so I'm sorry if I'm wrong, but I hope I helped :)
Good luck!
 
G5 -> SATA -> no master/slave :rolleyes:

I'd take a look at the setting in OF-variables, probraly just something wrong in boot-command.
 
iamsophie said:
I have no idea of this would apply to you, so please correct me if I am wrong, but could it be the jumpers on the drive?
I think that maybe you might have set the drive jumpers to "Slave" on the 640 and perhaps "Master" on the 500.
This is just an educated guess, so I'm sorry if I'm wrong, but I hope I helped :)
Good luck!
Click to expand...

The jumpers to a sata drive, control the speed of the drive. You can put a sata 3 drive in your G5, if it is slowed down to a sata 2.
 
GermanyChris said:
you can run SATA 3 without playing with the jumpers
Click to expand...

Some SATA III drives. Other refuse to work unless they are in SATA I or II mode. Other SATA III drives, particularly SSDs, simply refuse to work on a G5's native SATA ports no matter what.
 
Intell said:
Some SATA III drives. Other refuse to work unless they are in SATA I or II mode. Other SATA III drives, particularly SSDs, simply refuse to work on a G5's native SATA ports no matter what.
Click to expand...

My 7,3 booted just fine with an OCZ Agility 3
 
Note I did not say all SSDs. Only that they have a higher chance of not working. And one thing about the OCZ Agility 3, they come from the factory with the firmware set to SATA I compatibility mode. That's why it works fine in your G5.
 
Swap drives or battery, no fix

So this morning I tried putting in a new motherboard battery and swapping the drives around. Neither of these solutions appears to fix the problem. Also, I just noticed this morning that all the firewire ports are junk. When I plug an external hard drive in to transfer data, the drive is recognized fine. When I initiate the data transfer, it takes a ridiculously long time, and then the data becomes corrupted on the external hard drive.

Intell, I used to have an Intel x25m G2 in the G5 (native SATA bay), and it worked perfectly. I switched to the WD 640 black because it was larger and I couldn't really notice the speed difference on such an old machine.

Rabid, when I try selecting the correct drive via holding option at boot, the computer either hangs for 10+ minutes or will boot to a drive I did NOT select anyway.

At this point I think the G5 is on its last legs, and from the symptoms probably has a serious motherboard issue. She has lasted me 9 years though, so I don't feel that bad...
 
She's now dead.

Quick update - the machine is toast. When I press the power button, all I hear is a "click" from the power supply. No fans, no anything else. Time to retire.
 
uller6 said:
Quick update - the machine is toast. When I press the power button, all I hear is a "click" from the power supply. No fans, no anything else. Time to retire.
Click to expand...
I made my own Boo Boo not long ago that I am not proud of:

I installed my SATA BD in the quad using the bottom bays SATA port so the drive would be bootable. In order to cleanly run the cable I had to unplug the PCIe Power that goes to the the drives. I was in a bit of a hurry while doing it so I didn't pay much attention to reconnecting the PCIe power on the board (it felt wrong when I put it in) got the computer on my desk, connected everything and go nothing but a click when I hit the power button. Moral of the story re check you connections!!
 
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