fdisk - nejasnosti

[Milan Kopacka]

On Wed, 13 Jan 1999, Miroslav BENES wrote:

> fdisk mi ale vypise :
> 
>    Device Boot Begin  Start   End   Blocks   ID  System
> /tmp/hda1   *      1      1   261  2096451    6  DOS 16-bit >=32M
> /tmp/hda2        262    262   268    56227+  83  Linux native
> /tmp/hda3        269    269  1092  6618780   83  Linux native
> /tmp/hda4       1024   1093  1108   128520   82  Linux swap
> 
> K tomu mam dotazy :
> 
> 1) Jaky je rozdil mezi polozkami Begin a Start ? Proc je u hda4 mezi 
> nimi rozdil ? Vadi mu snad, ze by mel byt zacatek az za 
> hranici 1023 cyl ? Nebudou se oddily prekryvat ?

Partition mini-HOWTO uvadi:

> Some fdisks, noteable the DOS one, are somehow limited when they       
> have to deal with other operating systems partitions. Such limitations
> include the complete inability to deal with anything with a foreign
> type code, the inability to deal with cylinder numbers above 1024
> ..

Z toho vyplyva, ze Linuxovy fdisk kvuli kompatibilite nemuze zapsat do
part. tabulky adresu v C/H/S s cislem vetsim, nez 1024; zapise tam misto
ni 1024 a skutecnou adresu zapise v LBA formatu do jineho pole. V sloupci
Begin mate tedy zacatek podle C/H/S;  v polich Start a End skutecne
hodnoty.

> 2) Druhy oddil ma velikoct cca 56 MB. Proc je u poctu bloku znak "+" 
> ?

/usr/doc/util-linux-x.x/README.fdisk uvadi

> The `+' after three of the sizes warns that these partitions contain an
> odd number of sectors: Linux normally allocates filespace in 1 kilobyte
> blocks, so the extra sector is wasted.

Diskovy sektor ma 512 bytu, nejmensi alokovatelna jednotka na ext2
filesystemu je 1024B (1kB), takze je to takove varovani, ze prichazite
o 512 bytu z disku :)

zdravi

  Milan Kopacka