logical volume question

binary_0011 · 01-10-2007, 07:12 AM

hi guys,

when i do a lvdisplay /dev/vg00/lg01, it will show this :

LV Permission read/write
LV Status available/syncd
Mirror copies 1
Consistency Recovery MWC
Schedule parallel
LV Size (Mbytes) 1200
Current LE 300
Allocated PE 600
Stripes 0
Stripe Size (Kbytes) 0
Bad block on
Allocation strict
IO Timeout (Seconds) default

then I do a lvextend -l 400 /dev/vg00/lg01 , the LE will become 400 and PE will become 700.

I want to know what is the relation between logical extend and physical extend?

shouldn't PE be fixed ?

Thanks.

MensaWater · 01-10-2007, 09:46 AM

You sure PE didn't change to 800 rather than 700?

If it is mirrored then you have 400 LEs but twice as many PEs because you have 2 PEs for each LE.

binary_0011 · 01-10-2007, 11:44 PM

Quote:

Originally Posted by jlightner

You sure PE didn't change to 800 rather than 700?

If it is mirrored then you have 400 LEs but twice as many PEs because you have 2 PEs for each LE.

i see, because it is mirror so the extend will double, if it is not mirror the pe will not double.

MensaWater · 01-11-2007, 08:43 AM

Correct.

PE = "physical" extent. You have two "physical" disks for each extent.

LE = "logical" extent. Essentially this is "usable" space. So 2 GB mirrored = 1 GB "usable".

By the way it sounds as if you're discussing HP-UX. If so you should know there are other forums with higher visibility than this one for HP-UX.

HP has forums at itrc.hp.com.

Also there is a mailing list called Dutchworks. Details for it:
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For whatever reason the folks that run Linuxquestions.org don't seem to think HP-UX worthy of its own forum so there's no reason to use them for it.