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isolating a SAN

Because of some servers which are very heavy at some parts of the year, and bringing down the performance of other servers in the SAN, is it possible to isolate a part of SAN to specific server through SAN Volume Controller or any other way?

thanks
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anushahanna
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anushahanna
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1 Solution
 
robocatCommented:

It depends on the SAN you're using.

Some high-end SANs (such as NetApp) have Quality Of Service settings that allow you to assign individual priorities to different servers. This ensures that one server can not bring down performance of another server.

Low end SANs rarely offer such features.
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anushahannaAuthor Commented:
what are the options for low end SANs?

where do IBM based SANs stand, with regard to the above?
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robocatCommented:

>what are the options for low end SANs?

None, this is why you pay a premium price for high end SANs. The only option is not to consolidate too many servers on a single SAN box.

>where do IBM based SANs stand, with regard to the above?

IBM has both low and high end SANs. Amongst those they sell a rebranded Netapp, that can do this. You need to check with IBM for the specs of any specific box.
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anushahannaAuthor Commented:
do the Quality Of Service settings use only software based controls or hardware too?

thanks
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robocatCommented:

This is a software/firmware feature.
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anushahannaAuthor Commented:
would you say there is no hardware solution (yet) to isolate SAN.

thanks robocat.
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robocatCommented:

Not in the sense that you mean.

There is a concept of  isolation in Fibre Channel (FC) SANs  that is purely a security feature, to disallow one server accessing the data of another. But even that is software on some level.

But as far as performance and quality of service goes, this is by definition a feature of the internal SAN software.
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anushahannaAuthor Commented:
if you added a separate SAN controller for the server which is using most of the load, what is the benefit of effect of that?
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robocatCommented:

This probably will help, but it greatly depends on the architecture of the storage box.

Also if the bottleneck is not in the controller but e.g. in shared disk groups, you still can have problems.

This also goes against the idea behind storage consolidation and shared storage resources. Ultimately, you end up with a separate storage box for the most busy server and no more shared storage at all, loosing the flexibility and manageability a consolidated storage system has to offer.

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anushahannaAuthor Commented:
i agree to what you see as an hindrance to the consolidation idea; but if the one aspect of the environments brings down the stability of the SAN, i was wondering what are the options..

The performance and quality of service feature you mention, does it control by allocating more resources to the busy server? (like spindles)

do all san vendors call the feature 'quality of service' (HP, Qlogic etc)

thanks
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robocatCommented:

QOS is a pretty generic name, I'm not sure if vendors have specific names for this.

QOS is usually done by using priority queues. As an example, one could have a policy that says to throttle down IO requests from a low priority queue (by delaying requests) if there are requests in a higher priority queue. Higher priority queues will probably also get more resources like cache memory.

Queues can be allocated to specific servers or even specific applications, volumes and LUNs. Policies can be set to change e.g. based on the time of day (e.g. perhaps a certain app needs more IO when doing payroll).

This is probably all I can tell you about this, every vendor has specific ways of doing this and has different features. Check with vendor specs if you need specifics.
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anushahannaAuthor Commented:
Thanks a bunch robocat
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