What determines max no. of array & logical drives created?

[Panda]

I have the following from a customer:
Referring to the EXP 300 (SCSI storage expansion unit):
- What's the maximum# of array (RAID-1) supported ?
- What's the maximum logical drive can be created ?

I am trying to understand:
What determines the maximum no. of array supported? Is it the raid controller?

What determines the logical drive created? Is it the os such as Windows, Linux etc?

Appreciate any pointers.

 

[lej]

This is a complex question. I will try to provide an answer that is not as complex.

The # of arrays supported on a single RAID adapter depends on the controller used. for instance the IBM ServeRAID adapter supports 8 arrays under some conditions and less under others.

The # of drives per array can also be an issue depending on the stripe size selected.

The IBM SwerveRAID 4m, for example, has 4 channels and each channel supports 15 devices. That is a lot of drives for a single array and the house keeping task may take a bit of time to complete. IBM also publishes a White paper on RAID that may answer the question for the customer, If it is still available.

You also have to consider the largest partation and hard drive supported by the OS and system BIOS. It is possible the RAID logical drives may be configured larger than the OS or system BIOS can support.

Try to find out why the customer is asking the question. That will give us more to work with.

 

[catorze]

IBM has a great RedBook, "Netfinity Server Disk Subsystems" SG24-2098-03 that has tons of info. Section 4.2.1 has what you're looking for: Up to 15 HDDs per channel, limited by the enclosure; Up to 8 arrays per controller; Up to 8 logical drives per controller (one logical drive per array).

To answer your questions directly, the RAID controller determines the maximum number of arrays and the user chooses the type and size of Logical Drive via the RAID controller configuration utility.

 

[Panda]

Thank you very much for your responses. It helps a lot.