I have two internal hard drives in my G5 Powermac (10.4.8) and I mirror\nthe second with SuperDuper and it's bootable. Neither drive is\npartitioned. I'd like to be able to startup from the second drive and\nrun directory checks, etc. on the main drive with Disk Utility and\nDiskWarrior but both of these programs return error codes saying, in the\ncase of DU, "Verify volume failed with error Could not unmount disk\n(-10000)". DW says it can't access the volume because it is still in\nuse. Both DU and DW can access the second drive when started up from the\nfirst, however. If there's something I can do to make my main drive\nunmountable when the computer starts up from the second drive I'd\nappreciate hearing what it might be. DiskWarrior takes forever to start\nup the computer off its CD. Thanks.