topic Re: difference between logical and physical file system in Operating System - HP-UX

difference between logical and physical file system

Shivkumar — Tue, 16 Aug 2005 03:49:49 GMT

What is the difference between logical and physical file systems ?

Best regards,
Shiv

Re: difference between logical and physical file system

Joseph Loo — Tue, 16 Aug 2005 03:55:56 GMT

hi shiv,

u mean physical and logical volume? this doc give a good overview through it is a comparision of lvm and vxvm:

http://docs.hp.com/en/5187-1372/ch01s02.html

regards.

Re: difference between logical and physical file system

Devender Khatana — Tue, 16 Aug 2005 03:57:17 GMT

Hi Shiv,

In HPUx we have the terms called physical & logical volumes. Physical volume corresponds to a physical media like a physical disk or a raid LUN made visible to operating system. Whereas logical volume corresponds to a LVM logical volume which is made within a volume group.

One of the benefits of configuring storage using LVM is that one LVOL can spread across two or more disks and can be of size more than that of one physical disk.

Please revert back if your intention was to clarify something else ?

HTH,
Devender

Re: difference between logical and physical file system

Kurt Beyers. — Tue, 16 Aug 2005 04:09:47 GMT

A physical volume will correspond to a disk.

A logical volume is a 'logical' disk that can for instance span multiple physical disks or just be a part of a physical disk.

best regards,
Kurt

Re: difference between logical and physical file system

Mahesh Kumar Malik — Tue, 16 Aug 2005 09:50:59 GMT

Hi Shiv

Basically it is physical disk and logical volume. Logical volume enables to group multiple disk as one one identity and thus allowing the system to see multiple physical disks as one logical disk

Regards
Mahesh

Re: difference between logical and physical file system

Cem Tugrul — Wed, 17 Aug 2005 11:22:18 GMT

Shiv,
A physical volume refers physical disk.Lets
say you buy a new disk and plug it on your system so when you run ioscan -fnCdisk;
you have to see similar like;
/dev/dsk/cXtYdZ
so this your new disk address but UX systems
needs raw device files for disks so you have
to create with the command;

#pvcreate /dev/rdsk/cXtYdZ

and this time when you run again ioscan -fnCdisk command both you see 2 address for your new disk like;
/dev/dsk/cXtYdZ /dev/rdsk/cXtYdZ
so this means you are ready to use this disk
whatever you want(extending vg-creating new vg for this disk-mirroring...)
just take care the status of the new disk(s)
must be always "CLAIMED" as your present disks...

A logical volume is analogous to a partiton.A
logical volume must be created in order to use the space in a volume group for a filesystem,swap area,or raw partition and you can easily chose the logical volume.

logical volumes can;
i)encompass all or any portion of the space on an LVM disk

ii)span LVM disks

hope it is clear now,

Good Luck,

Good Luck,