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EVA considerations building new LUNS

Dave Chamberlin
Trusted Contributor

EVA considerations building new LUNS

Greetings - I have an EVA4400 connected to production Oracle on rp7420. There are about 20 volume groups, each with a single lv, mounted as 20 disks.  Many of the vol groups have been extended over time with smaller luns added. I need to add more space, and want to replace the smaller luns with much larger ones, create fewer volume groups and use more lvs per vg (say 2 for each vg), but leave the same number of mount points. In the olden days, I used to optimize disk performance by separating indexes from data, etc when disks were stand-alone devices. Do I still need to worry about this if there are competing indexes and data within the same LUN on the EVA? Will I take a performance hit by combining the smaller LUNS into larger ones?  Thanks for your thoughts.

3 REPLIES
Torsten.
Acclaimed Contributor

Re: EVA considerations building new LUNS

I would not do this.

 

Your data resides on all disks within the diskgroup, no matter how many vdisks (LUNS) you created.

 

I assume you still use hp-ux 11.11 or 11.23 without load balancing, so you should better "balance" the paths to the primary controllers (in other words - don't force all the traffic over a single path and controller).


Hope this helps!
Regards
Torsten.

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Dave Chamberlin
Trusted Contributor

Re: EVA considerations building new LUNS

I do certainly have multiple paths/controllers. The real question is really many smaller luns, or fewer larger luns - will this reduce performance if there are contentious tables within the same lun (as opposed to a different one as now)?

Jan Soska
Honored Contributor

Re: EVA considerations building new LUNS

Creating more smaller lun (which run all on the same disk group) has probably only one advantage - each lun will have its own queue from host operating system point of view. So, if you aplication is able to fill luns queue during operation, use more luns - but it must be very i/o intensive aplicatio. Otherwise it makes no sence, just complicates system.

 

Jan