Virtual Copies on a 3PAR 7400

[Berd]

Hello Peers, 

When creating read/write Virtual Copies on a 3PAR 7400, should I be concerned by the additional load that read activity will place on the parent of the VC ?

For example, we create a fresh VC each batch run to produce a copy of our Production Database, and then run datawarehouse extracts on the VC. In reality, will the reads not be producing an additional load on the parent vDisks ? 

And if they do, how do you quantify a safe number of VC's ? Or is it a case of suck it and see ?

Hope someone can shed some light on this.

Berd

[Dennis Handly]

I don't think the load will be that bad.  You have to read the data from somewhere.

And since the data is scattered all over chunklets, you may not know the difference.

[Berd]

Thanks Dennis, my thoughts were similar in that given that the 3PAR is spreading chunlkets across all spindles therefore  hot disks are not likely, but you could still have hot chunklets, right ??? 

HP Docs state that you can have 512 read only Virtual Copies of the parent or 256 read/write copies without impacting performance. This seems quite a claim, was wondering if anyone had pushed their environment to this limit in the 'real' world ;-)

Berd

[Sheldon Smith]

While it is not impossible to have "hot chunklets",  not only does the 3PAR spread chunklets across all spindles, it spreads steps across chunklets. Hot chunklets are very unlikely.