redhat disk alignment

I know, but if you take a look at the Linux Connectivity Guide you'll see that the example made for creating a PV is on a partition from a while disk, not an actual disk.

That is also the case with Oracle ASM - except that if you use ASM it actually forces you to create a partition and use it for your ASM disk.

LVM let's you do it both ways.

PV is the physical volume (LUN) you add to LVM(VG). So as long as you dont create a LV(logical volume) on  PV , the PV  can be considered as entire disk. Partition(fidsk, parted) comes to picture when there is  no tool like LVM  to take care of the partition.

I do belive that if you whant to get the max out of the Symmetrix / DMX / V-MAX (or any other vendors arrays) cache you need to align all x86 OS'es (including readhat) so that the 4K cache boundery in the array stay happy and you will get better responce times from your devices :-)

[root@localhost ~]# parted /dev/sdb
GNU Parted 1.8.1
Using /dev/sdb
Welcome to GNU Parted! Type 'help' to view a list of commands.
(parted) unit s
(parted) print

Model: APPLE Xserve RAID (scsi)
Disk /dev/sdb: 976748543s
Sector size (logical/physical): 512B/512B
Partition Table: msdos

Number Start End Size Type File system Flags
1 63s 976735934s 976735872s primary

(parted) rm 1
(parted) mkpart primary 128 976735934
(parted) print

Model: APPLE Xserve RAID (scsi)
Disk /dev/sdb: 976748543s
Sector size (logical/physical): 512B/512B
Partition Table: msdos

Number Start End Size Type File system Flags
1 128s 976735934s 976735807s primary

(parted) quit
[root@localhost ~]#

/Lars