topic Re: XP24000 in Disk Enclosures

XP24000

Sivakumar MJ._1 — Fri, 27 Mar 2009 12:00:29 GMT

What is the Maximum Number of hosts that can be connected to a Single CHIP Port.

Apart from considering the total no. ldevs for per host or size presented to the host per chip port, what is the maximum number of hosts that can be connectd to a chip port...

Re: XP24000

IBaltay — Fri, 27 Mar 2009 12:15:04 GMT

Hi,
the theoretical max is 256 host groups per CHIP port...

Re: XP24000

Sivakumar MJ._1 — Fri, 27 Mar 2009 12:23:37 GMT

Thanks IBaltay,

If its 256 hosts per CHIP port, what is the maximum size of Luns that can be presented to each host in the Same Chip port and how m uch is supported.. Is there any specific Thumbrules or best practices in configuring available..

Let me know pls.

Re: XP24000

IBaltay — Fri, 27 Mar 2009 12:55:57 GMT

Hi,
it comes from the max number of LUNs=65280 and max number of CHIP ports=224

Re: XP24000

Nigel Poulton — Fri, 27 Mar 2009 14:20:57 GMT

Sivakumar MJ,

Before I go any further - IN THE REAL WORLD MOST PLACES ATTACH BETWEEN 10-20 HOSTS PER CHIP PORT. You should use this as a general rule of thumb unless you know you IO profiles very well.

Now for the comments you have received so far.......

IBaltay actually said that you can create a theoretical maximum of 256 "Host Groups". However, each Host Group can contain multiple Hosts.

The theoretical, but totally unrealistic, limit is - 2048 hosts per port (you would/could never do this).

The above is based on the following -

Each CHIP port on the XP2400 has a certain number of 2048 tags/queues. This basically means that each CHIP port can accept 2048 I/Os before overrunning the port.

So if you had 2048 hosts each host could only issue a single I/O simultaneously (2048 I/Os in total). If each of the 2048 hosts issued two I/Os at the same time the port would be overrun.

This is all theoretical as you would never go anywhere near that number of hosts per CHIP port.

In the real world, the number of hosts per CHIP port depends on a lot of things such as each hosts -

required throughput MB/s
required IOPs and I/O size
......

IN THE REAL WORLD MOST PLACES ATTACH BETWEEN 10-20 HOSTS PER CHIP PORT.

But this is just a guideline and it depends on the factors mentioned above such as MB/s and IOPs....... You should monitor the performance of each port to make sure that it is not becoming a bottleneck.

As for how many LUNs you can present on each CHIP port..... Again, this is theoretically 2048. You can map 2048 LUNs per CHIP port but because of the 2048 tag limit each LUN could only accept one I/O simultaneously without overrunning the port.

A general rule, if you dont know your host and LUN I/O profiles would be to keep the number of LUNs per CHIP port well below 2048.

Hope this helps.

Re: XP24000

Sivakumar MJ._1 — Fri, 27 Mar 2009 14:31:05 GMT

Nigel (mackem) & IBaltay, Do I get any solid supportive materials to present it to my customer regarding this valuable points that you put forward...

Re: XP24000

IBaltay — Fri, 27 Mar 2009 14:53:25 GMT

hi, here is the XP24k manual page, maybe you can find something useful here:
http://h20000.www2.hp.com/bizsupport/TechSupport/DocumentIndex.jsp?contentType=SupportManual〈=en&cc=us&docIndexId=64179&taskId=101&prodTypeId=12169&prodSeriesId=3418595

Re: XP24000

Nigel Poulton — Fri, 27 Mar 2009 15:14:12 GMT

You wont get enything solid on this because it is a very subjective topic. That is, it depends totally on how powerful your hosts are and how hard they will push the CHIP ports.

Ive seen configurations where a single very powerful host has several dedicated prtos (less than one host per port).

But Ive also seen configurations where there are over 20 hosts per port. But these hosts were not very powerful Windows servers....

If you have a high performance host then dont put it on a port with lots of other hosts.

The trick is to monitor your ports and know the performance requirements of your connected hosts.

Re: XP24000

Sivakumar MJ._1 — Sun, 29 Mar 2009 18:47:09 GMT

Got effective ideas from IBaltay & Nigel (mackem)