Pvcreate options for Symmetrix disks

[Rowan Brook]

Should "pvcreate -d 0 xxx" (soft defects) be used on symmetrix disks, considering that all LV's created on it should have Bad block reallocation set to none?

[Michael Tully]

Hi,

This should only be done at the logical volume level and not pv level if your using LVM.

e.g.
# lvcreate -n lvname -r N /dev/myvg

I remember EMC explicitly telling me this on the delivery of our last Symmetrix.

HTH
Michael

[Sridhar Bhaskarla]

Hi,

You are going to use "-r N" anyway while creating the logical volumes.

So, it does not matter if you used "-d" option with pvcreate.

So, go ahead with default options.

-Sri

[monasingh_1]

I think even if you do it, it is not going to hurt in any way. but I will not do it.

Other thing is if you are turning off bad block relocation on Lvols, why would you like to give -d 0 anyway..

you do not need to force -d 0 becasue I doubt you will ever find any bad block since EMC will internally do it before HPUX becomes aware of it.

[Rowan Brook]

Thanks for the information, I should clarify the question slightly by saying do I gain more disk space by not reserving the space and how do you calculate how much?

[monasingh_1 · Accepted solution]

I do not think you save any space because every disk has an area for the informations like this and is not available to user any way. Long ago I used to work on motorola based machines and there you could actually see this table from certain way (kind of from ISL) and the table was well outside the regular usable area.

This one was a good question though, check the doc ID UNX1010055..

hope this helps..