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Changes to multipath disks

Andrew Young_2
Honored Contributor

Changes to multipath disks

Hi

I have a BL460c blade running RHEL 4u7 connected to an EVA8100. Currently I have been using a single LUN but this is now proving inadequate and I need to allocate additional space.

The options available are to increase the existing size of the disk on the EVA or adding another disk onto the EVA for use by this server. Thereafter I could either add it to the existing VG or create a new one.

My first question relates to which is the best option and why? Obviously adding new disk on a seperate VG is the least risky but some sagely advice would be appreciated.

My second question, if I do add an additional disk is there a way of getting RHEL to recognize the disk without rebooting?

Thanks in advance.

Andrew Y
Si hoc legere scis, nimis eruditionis habes
4 REPLIES
Steven E. Protter
Exalted Contributor

Re: Changes to multipath disks

Shalom,

Present a new LUN.

These systems, whether they run HP-UX or Linux are notorious for having problems recognizing space increases on existing LUNS.

I've struggled with this issue enough times, so learn from my pain.

SEP
Steven E Protter
Owner of ISN Corporation
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http://hpuxconsulting.com
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mohamed.bouraoui
Frequent Advisor

Re: Changes to multipath disks

Hi friend;
Itâ s preferable to add another disk via another controller of EVA, because these methods increase the performance of read/write on those LUN.
Good luck
Andrew Young_2
Honored Contributor

Re: Changes to multipath disks

Hi

Stephen I agree with the increasing disk sizes as I have been burned on HP-UX too, but there was always hope that it would work. But adding another LUN seems the best option.

Mohamed I am using the multipath drivers already, however since this is going to be for cvs and subversion performance is not an issue here.

I have also found this thread on adding LUNS with needing to reboot.
http://forums13.itrc.hp.com/service/forums/questionanswer.do?admit=109447627+1240569755262+28353475&threadId=1170635

Regards

Andrew Y
Si hoc legere scis, nimis eruditionis habes
Matti_Kurkela
Honored Contributor

Re: Changes to multipath disks

Depending on the version of your HBA drivers, the new disks might be recognized automatically.

If they aren't, there are ways to make the driver recognize the new disks and/or forget the old ones without rebooting. Please see:

http://kbase.redhat.com/faq/docs/DOC-3942

MK
MK