erased partition problem

[jhoussock]

hey guys i had three partitions set up on my hard drive...1st was windows 2nd a fat for shared storage and third for leopard...i wanted to start tinkering with snow leo and i erased my windows partition and formated to extended journal my leo partition immediatly disappeared of disk utility and will no longer show up can i only have one extended journal partition on my hard drive and can i recover that partion some how? thanks in advance

[srs5694]

You can definitely have multiple OS X partitions (filesystem is unimportant) on one hard disk. Whether and how easily you can recover depends on the nature of the error. If the partition disappeared because its type code changed, that's very easily corrected with utilities such as fdisk (for MBR disks) or gpt or gdisk (for GPT disks). If the partition was deleted after the new one was created, then it may be possible to guess at its correct location and size with the same utilities (fdisk, gpt, gdisk), but that's risky. GNU Parted (available on many Linux emergency discs) has a partition-finding option that may help, although my own experience with this has been that it's rather unreliable. I'm sure there are other products with similar features. If the new partition spans the space of the original two partitions, finding the exact size of the original will be that much harder.

 

In the future, back up your partition tables. For MBR disks, this is easily accomplished with dd:

 

dd if=/dev/disk0 of=backup.mbr bs=512 count=1

 

Be sure to get the if and of options right, though; mixing them up will be disastrous!

 

For GPT disks, it's tougher. You can get a list of partitions and their start and end points with many utilities and copy the data to a file, but be sure you've got data that's exact to the sector; something like "2.2GB to 4.3GB" is so imprecise that it's next to useless. Alternatively, gdisk has a tool to save a binary backup file (it can restore its own backups, too).