topic XP 12000 front end thresholds in Disk Enclosures

XP 12000 front end thresholds

qvcc — Wed, 25 Jul 2007 08:55:03 GMT

Can anyone provide any information as to what the thresholds are on the CHIPs. In other words when should I expect to see a bottleneck?

We have a situation in which we assigned one CHIP (on each side) to a server. Just two disks on that server can generate max I/O at 8600 at a rate of 240 MB/sec. The data chunks are at around 32k and 98 percent reads.

Currently we are seeing CHIP utilization at over 75 percent.

Lastly, is there a calculator to determine how many CHIPs should be assigned based on throughput and workload? Is there an XP calculator or other utilities than can assist with workload calculation?

Thanks

Re: XP 12000 front end thresholds

Amar_Joshi — Wed, 25 Jul 2007 12:30:03 GMT

I was told that XP12000 CHIP port can easily handle upto 6000 IOPS but again it remains a guideline. There are more factors to consider, first of all CHIP PORT MP (microprocessor) utilization, if you meant to say MP is 75%, it is usually hitting the threshold (though I have seen them working till 90-95%). Secondly, throughput has to be under limits. If you are saying 240MB/s for a 2GB fiber link, it is touching the bottleneck. Third major is IOPS, what kind of IOs? Random has to be lower than 6000 IOPS but sequential can be higher than that. How high? depends on how many disk spindles are working for those IO requests. If you are using 10k RPM disks, each disk can serve 125 random IOPS and 15k RPM disks can server 150 IOPS (a rough figure but you can rely on them).

All I want to say that you can hit the bottleneck anywhere in the system:
- Host port IO handling
- Host port bandwidth
- Host port CHIP MPs
- HDD response
- Type of RAID (RAID6 is slowest, RAID5 is slower than RAID1)

Hope that helps.

Re: XP 12000 front end thresholds

qvcc — Wed, 25 Jul 2007 15:20:25 GMT

Thanks for the response. But I would really like to hear from someone who has specifics and not speculation. In other words, where can I find this in a document from HP.

qvcc

Re: XP 12000 front end thresholds

chris callihan — Wed, 25 Jul 2007 22:35:53 GMT

there were a couple of different CHIP cards available for the XP12000, which part number do you have? I don't have the part numbers handy, but the first revision of the 4Gb card did have a max throughput of approx what you are seeing (this was documented in the XP quickspecs at the time).

Re: XP 12000 front end thresholds

Amar_Joshi — Thu, 26 Jul 2007 14:34:35 GMT

HP participation is very low here and specially for such requests, with my previous experience and the time I spend in this forum you will not get anything like that. Another reason for not having such document is that whatever number comes out from it, still remains a guideline and not the perfect answer for you to rely on because performance is a vast study which has lot many factors to consider.

Don't compare an enterprise storage with harddisks which can have straight answers for you.

Re: XP 12000 front end thresholds

Amar_Joshi — Thu, 26 Jul 2007 14:53:26 GMT

Attaching the HP Official document which recommends a max of 2545 IOPS per MP (not per port). see page 17.

Re: XP 12000 front end thresholds

qvcc — Fri, 27 Jul 2007 08:49:09 GMT

Cool! thanks for the help..

Re: XP 12000 front end thresholds

Amar_Joshi — Sun, 29 Jul 2007 15:44:02 GMT

You are welcome, glad if it works for you.

Another way of saying thanks is by giving away points.