RE: "what is a partition table?"
For historical (and practical) reasons, your hard drive is not treated the same way as say, a floppy diskette. (Yes. ancient tech.) A floppy diskette is treated as a raw storage medium with a given number of sectors, and the filesystem structures are assumed to always be in certain places on that medium. A hard drive however, is not treated this way. Instead, there is ONE fixed structure at the start of the disk which contains a table of what chunks of sectors are allocated. Such allocations are called "partitions". There are now two major kinds of partition table used by commodity computers today. Old fashioned MBR (Master Boot Record) and GPT (GUID Partition Table). MBR is used by old school BIOS based systems, and is stored on the very first sector of the drive. It has provisions for up to 4 primary partitions, has a bitfield that stores which of these partitions is "active" (eg, bootable), and uses a 2byte identifier to describe what kind of partitions are present. It stores what the start and end sectors are for every partition in the table. On old-school bios systems, the BIOS loads this sector as part of the boostrap process, which then tells the BIOS routine where to read on the hard drive to load the operating system's boot sector. It then passes control over to the OS loaded from that boot sector, and the OS reads the table again, and determines if it should make use of the other partitions are not. (eg, show them as drives, or ignore they exist)
GPT is much newer, and is for EFI and UEFI based systems. It uses the first 4mb of the drive to store a fake MBR (for back compatibility with older OSes), and then a table for what partitions are defined, and then uses (typically) 100mb of space to house a special FAT32 volume that holds bootloaders. EFI provides very different services than the old fashioned BIOS, including advanced disk access, and partition enumeration/reading. The firmware itself has a spacious nonvolatile area for storing boot parameters for a potentially long list of operating systems. Each entry in the NVRAM states what the main partition for that OS is, and what loader (stored in the 100mb fat partition) to use. It has many advantages, in that it can support much larger partitions and disks (MBR tanks out after 3tb or so, due to how the spec was made in days of yore), but is also more troublesome to deal with than MBR. (MBR is very minimal, no-nonsense.)
Regardless of what kind of table your drive is using, the table that keeps track of partitions stored at the top of the drive is called the partition table. When I suggested dumping the table, I meant wiping its contents, or re-creating the table from scratch using a disk utility of some kind. (such as that built into the windows install cd)
This causes all areas on the drive to be treated as empty space, allowing you to install absolutely fresh and clean.
Reelya pointed out that the restore volume (what gets executed when you hold down the magic buttons for your system) is defined in the partition table, and dumping the table will destroy this volume, rendering it inoperable.
I responded that yes, this is true, but I never want to use that partition anyway, and create a brand new one with a recovery image I create myself that is clean and free of nasty bloatiness instead (and gave a link detailing how to make one.)
If you need to ask what a partition table *is*, then you probably have no business attempting the kind of advanced stuff I mentioned in creating a brand new recovery volume, and should probably not dump the table.
Author
Topic: The Generic Computer Advice Thread (Read 573713 times)