It's 64 because it's the lowest sector that is a multiple of 4kB.
sector 63 is the lowest possible
you can see the result of that choice, using sector 64, the
corresponding cylinder is 1, so the drive is well aligned^^
sudo fdisk -l /dev/sda
WARNING: GPT (GUID Partition Table) detected on '/dev/sda'! The util
fdisk doesn
't support GPT. Use GNU Parted.
Disk /dev/sda: 2000.4 GB, 2000398934016 bytes
255 heads, 63 sectors/track, 243201 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000
Device Boot Start End Blocks Id System
/dev/sda1 1 243202 1953514552 fd Linux raid autodetect
sudo fdisk -lu /dev/sda
WARNING: GPT (GUID Partition Table) detected on '/dev/sda'! The util
fdisk doesn
't support GPT. Use GNU Parted.
Disk /dev/sda: 2000.4 GB, 2000398934016 bytes
255 heads, 63 sectors/track, 243201 cylinders, total 3907029168 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: 0x00000000
Device Boot Start End Blocks Id System
/dev/sda1 64 3907029167 1953514552 fd Linux raid autodetect
i think i found this setting on that page but not really sure
http://ubuntuforums.org/showpost.php?p=9134230
2011/7/21 Paweł Brodacki <pawel.brodacki@xxxxxxxxxxxxxx>:
> 2011/7/21 Erwan Leroux <erwan.lerou@xxxxxxxxx>:
>> following is how i configured advanced format drives for raid 5
>> i created one partition on each disk
>>
>> fdisk -u /dev/sdX
>> # -u change the unit displayed by fdisk to sector instead of
>> cylinders, this way it's easier to configure
>>
>> # the table partition isn't really modifier until you send the w
>> command, so if you messed up use the q to quit and restart
>>
>> #delete first partition of the disk, repeat until you had cleared the disk
>> d
>>
>> # create a new partition
>> n
>>
>> # select primary parition
>> p
>>
>> #select number one (don't know if number is important, i guess it's
>> means /dev/sdX1)
>> 1
>>
>> #select first sector, here is the catch, to properly align the disk, select 64
>> 64
>>
> Why do you choose 64? One physical sector (4KiB) is 8 logical sectors
> (512 B). Would any number greater or equal to 8 and evenly divisible
> by 8 work as well? Are you aiming to align partition start with RAID
> chunk boundaries?
>
> Just curious.
>
> Paweł
> --
> To unsubscribe from this list: send the line "unsubscribe linux-raid" in
> the body of a message to majordomo@xxxxxxxxxxxxxxx
> More majordomo info at http://vger.kernel.org/majordomo-info.html
>
--
To unsubscribe from this list: send the line "unsubscribe linux-raid" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
