Aligning partitions on "advanced format" WD hard disks.
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Aligning partitions on "advanced format" WD hard disks.
Hi guys,
I'm aware that this has been already discussed around here (thread: http://www.linuxquestions.org/questi...drives-792046/ ) but it didn't give quite final answers on the subject + the fact that I've read a bunch of different stuff on other places which even makes me more confused.
Supposedly, the recent versions of fdisk on Fedora 13 and Ubuntu 10.04 are supposed automatically to solve these things around 4k sector aligment thing if one starts fdisk with -u and -c flags. But I'm getting confused as the heads / sectors informations always differ every time I create a partition.
Here's an example.
I have WD Green 1.5TB disk. I want 2 partitions. sdb1 with 1.3TB and sdb2 with the remaining space. Here's how it looks like.
When I create the first partition (1.3TB one), I get following listing with fdisk:
Code:
# fdisk -lu /dev/sdb
Disk /dev/sdb: 1500.3 GB, 1500301910016 bytes
78 heads, 37 sectors/track, 1015342 cylinders, total 2930277168 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x000e5602
Device Boot Start End Blocks Id System
/dev/sdb1 2048 2726299647 1363148800 83 Linux
Then I create the second, sdb2 partition with the remaining space on the disc.
After that, all of the sudden, I get the following info:
Code:
# fdisk -lu /dev/sdb
Disk /dev/sdb: 1500.3 GB, 1500301910016 bytes
255 heads, 63 sectors/track, 182401 cylinders, total 2930277168 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x000e5602
Device Boot Start End Blocks Id System
/dev/sdb1 2048 2726299647 1363148800 83 Linux
Partition 1 does not end on cylinder boundary.
/dev/sdb2 2726299648 2930277167 101988760 83 Linux
Partition 2 does not end on cylinder boundary.
Please note that number of heads and sectors / track changed to 255 / 63 + the fact that the program is complaining about the cylinder boundary. What's the deal? This is very frustrating!
If you're being picky, make friends with another disk formatting program - fdisk is not picky.
That said, there's actually 2 heads, many more sectors per track etc. The thing is that the first disks were 10MB, and that was huge - nobody could ever fill that in the life of a pc (or a hard disk :-). So they wrote a standard that allowed, iirc, 1023 tracks, 16 heads, and 63 sectors per track, which allowed 512MB of a hard disk. That was the limit in the nineties, and they've been bodging that ever since: LBA took us to 2 Gigs, CHS took us a bit further and the latest I have lost interest in. Depending on whether you read the same information under one of these bodges, you get different information.And everything is backwards compatible.
Ignore the heads, and the track not ending on a cylinder boundary. Ignore 63 sectors, and the number of tracks - they're all lies. What to doo is count the cylinders, and make a partition as an appropriate number of them. fdisk and other partitioning tools let you do it that way. Then don't listen to them.
Ok, so basically you are saying the results I posted are "okay" and I'm ready to go?
Quote:
Originally Posted by business_kid
If you're being picky, make friends with another disk formatting program - fdisk is not picky.
That said, there's actually 2 heads, many more sectors per track etc. The thing is that the first disks were 10MB, and that was huge - nobody could ever fill that in the life of a pc (or a hard disk :-). So they wrote a standard that allowed, iirc, 1023 tracks, 16 heads, and 63 sectors per track, which allowed 512MB of a hard disk. That was the limit in the nineties, and they've been bodging that ever since: LBA took us to 2 Gigs, CHS took us a bit further and the latest I have lost interest in. Depending on whether you read the same information under one of these bodges, you get different information.And everything is backwards compatible.
Ignore the heads, and the track not ending on a cylinder boundary. Ignore 63 sectors, and the number of tracks - they're all lies. What to doo is count the cylinders, and make a partition as an appropriate number of them. fdisk and other partitioning tools let you do it that way. Then don't listen to them.
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