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Is there a performance penalty with MirrorDisc/UX on K460 system with Jamaica disc drives?

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Randy Hagedorn
Regular Advisor

Is there a performance penalty with MirrorDisc/UX on K460 system with Jamaica disc drives?

We have just installed an HP9000 K460 system with Jamaica disc drives and are considering using MirrorDisc/UX for data replication. Will we pay a penalty in performance utilizing this software? If, so what would be a better option for replication?
5 REPLIES
Rita C Workman
Honored Contributor
Solution

Re: Is there a performance penalty with MirrorDisc/UX on K460 system with Jamaica disc drives?

Well....I have some K570's with the same. And I am not aware of a performance penalty (maybe someone else knows something more on this...)
BUT...even if there are...the benefits of mirroring your disks FAR outweigh it.
I have my o/s drives in the Jamaica box....and for everything else the boxes are fibered to an EMC disk array (that mirrors).
Works pretty good for us.
.
Patrick Wallek
Honored Contributor

Re: Is there a performance penalty with MirrorDisc/UX on K460 system with Jamaica disc drives?

I have not noticed any degradation in performance due to mirroring with MirrorDisk/UX. I have a K460 and everything seems to run fine. I don't get many complaints about performance.

I agree with Rita though that a slight degradation in performance is more than made up for by the increase in redundancy you get with mirroring.
Dave Wherry
Esteemed Contributor

Re: Is there a performance penalty with MirrorDisc/UX on K460 system with Jamaica disc drives?

I've used mirroring and not noticed a performance penalty. However, it could cause a problem. It depends on the activity on your system.
For reads you can actually get better performance. The read request is serviced by the "more available" disk. That may not be the best term. Basically, read requests are queued and put on the shortest queue. The system does a pretty good job of balancing the requests.
For a system that is very write intensive, performance could suffer. Every write has to be done twice. You are doubling your I/O's. It goes to the primary and then the mirror. A data acquisition system, such as recording stock transactions could suffer.
Unless you are just streaming writes to those disks I doubt that it will give you a problem. I agree with the others that the redundancy is worth the load it creates.
Carlos Fernandez Riera
Honored Contributor

Re: Is there a performance penalty with MirrorDisc/UX on K460 system with Jamaica disc drives?

Data protection is such important ( or more) as performance; and penality is not high.


You must think how to reduce impact of mirroring in performance, increasing security. To do this there are a few simple rules:

1- Use diferents SCSI cards for 'main' copy and mirror copy if posible.

2- Put more updated lvol on faster disks

3- Try to use -D y option when create lvols.

unsupported
Edward Sedgemore
Trusted Contributor

Re: Is there a performance penalty with MirrorDisc/UX on K460 system with Jamaica disc drives?


Ther performance penalty for using MirrorDisc/UX is very small. Basically you double the number of writes as now writes have to go to 2 disks instead of 1. As long as you have the primary and mirror disks on separate SCSI channels then you wont notice any performance penalty at all. If your primary and mirror are on the same SCSI channel then you may notice a performance penalty.