While the APM documentation covers SANs, the information is not all found in the same place. This KB also covers some additional questions.
Q. Specifically I need to know if it is okay to share a single SAN share across all the collectors to store the data and traces?
A. Yes. You need to set up a logical disk (LUN) per dedicated disk.
Q. Also is it okay to put binaries on the SAN share and have local configuration files?
A. Yes. As long as EM can access the files, that should be okay.
This is what is in the documentation:
Plan for SmartStor Storage Using SAN
The most important consideration for SmartStor disk storage is that the I/O path is free of contention, and that performance is fast and consistent. In a SAN storage environment, the optimal configuration maps each SmartStor to a unique logical unit number (LUN) that represents a dedicated physical disk. With this configuration, it is safe to set introscope.enterprisemanager.smartstor.dedicatedcontroller=true.
If you have configured two or more LUNs to represent partitions or subsets of the same physical disk, this configuration does NOT meet the requirements for a SmartStor dedicated disk
Enterprise Manager File System Requirements
The performance of the Enterprise Manager internal databases: SmartStor, baselines.db, and traces.db, is dependent on disk I/O performance. Place these databases on local or or high-speed SAN. Network File System (NFS) storage is not recommended.
SAN EM Properties
If you are using a local dedicated disk or a dedicated SAN logical unit number (LUN) for SmartStor, set the introscope.enterprisemanager.smartstor.dedicatedcontroller property to true.
Set this property in the IntroscopeEnterpriseManager.properties file.