----- Original Message ----- From: "Paolo Alexis Falcone" <[EMAIL PROTECTED]> To: <[EMAIL PROTECTED]> Sent: Monday, March 24, 2003 8:55 PM Subject: Re: [plug] partition slices in Linux
> Hmmm... haven't tried that. So it is safe to ignore the warning that > fdisk generates when an active disk is being repartitioned. yes as long as you entered the correct partition value > If I > remember right, the boot sector contains descriptors for primary > partitions/extended partitions, wherein these descriptors contain > pertinent information (start/end CHS, partition type, boot indicator, > number of cylinders and sectors). So once an fdisk operation is > committed, information about the new partition layout is written to the > boot sector, particularly the partition descriptors. again you are confuse of the proper term here... what you mean of boot sector in your statement above is actually the master boot record (MBR).. mbr is different from boot sector.. mbr is a sector where the *partition table* resides while boot sector is the *first sector* of that *partition* to continue the boot process after the mbr transfer the program control to it... mbr is always located at cylinder 0, head 0 sector 1 or the first sector of your disk.. a sector is usually 512 bytes long... for mbr, the first 446 bytes is called *initial program loader* (IPL), the next four records of 16 bytes each is the partition table and the last two bytes is the magic number... each record of the partition table consist of the followings: 1. active state - 1 byte 2. starting CHS - 3 bytes 3. type - 1 byte 4. ending CHS - 3 bytes 5. starting sector - 4 bytes 6. number of sectors - 4 bytes > I was under the impression that on the IA32, the total number of > partitions that can encapsulate filesystems (primary and logical) is > limited to 16 for IDE hard disks and 15 for SCSI hard disks (I'll check > out the documentation - actually the first one I got was similar to your > answer, while the second source I've got mentions the IDE/SCSI limit on > the number of partitions - frankly I'm trying to sort out what to > believe in and place in my final thesis documentation, as these two > documents are quite conflicting). Anyway, thanks for the clarifications. ok as what i explain above, mbr consist of four records.. it can be in the form of four primary partitions or three primary partitions and one extend partition... extended partition is actually called *extended mbr* (EMBR)... inside EMBR is the same as MBR except that it only contain two partition records compare to four records for MBR and those records are 1. primary partition and 2) another extended partion or EMBR... therefore with this scheme, you can have as many extended partitions as long as your number of sectors on your disk is exhausted... fooler. _ Philippine Linux Users Group. Web site and archives at http://plug.linux.org.ph To leave: send "unsubscribe" in the body to [EMAIL PROTECTED] Fully Searchable Archives With Friendly Web Interface at http://marc.free.net.ph To subscribe to the Linux Newbies' List: send "subscribe" in the body to [EMAIL PROTECTED]
