In a point-to-point configuration, only one ID can be assigned to each host channel. If more than one ID is assigned, the point-to-point protocol rules are violated. Any host channel with more than one ID will not be able to log in to an FC switch in fabric mode. This “one-ID-per-channel” requirement is true in both single-controller and dual- controller configurations. Thus, in dual-controller configurations, either the primary or the secondary controller can have an ID assigned, but not both. This yields:
(4 host channels) X (1 ID per channel) X (32 LUNs per ID) = 128 maximum addressable LUNs in a fabric point-to-point environment. If dual paths are desired for each logical device, a maximum of 64 dual-pathed LUNs are available.
In an FC-AL configuration, multiple IDs can be assigned to any given host channel. Although it is possible to add more, it is preferable that no more than four IDs be assigned to a controller on a given host channel. Thus no more that eight IDs should be assigned to any host channel if both primary and secondary controllers each have four IDs. This yields (4 host channels) X (8 IDs per channel) X (32 LUNs per ID) = 1024 maximum addressable LUNs in a FC-AL environment. However, configuring the maximum number of LUNs increases overhead and can have a negative impact on performance.
The FC-AL protocol should be selected for environments needing more than 128 LUNs, or where a switched fabric network is not available.
Supported RAID Levels
There are several RAID level choices: RAID 0, 1, 3, 5, 1+0 (10), 3+0 (30), and 5+0 (50). RAID levels 1, 3, and 5 are the most commonly used. The Sun StorEdge 3510 FC array supports the use of both global and local spare drives in the unlikely event of disk failure. It is good practice to use spare drives when configuring RAID devices. Refer to the Sun StorEdge 3000 Family RAID Firmware 3.27 User’s Guide, Sun StorEdge 3510 FC Array (P/N 816-7934) for detailed information on how RAID levels and spare drives are implemented.
Logical Drives
A logical drive (LD) is a group of physical drives configured with a RAID level. Each LD can be configured for a different RAID level.
The Sun StorEdge 3510 FC array supports a maximum of eight LDs. A LD can be managed by either the primary or secondary controller. The best practice for creating LDs is to split them evenly across the primary and secondary controllers. The most efficient maximum configuration would have four LDs assigned to each controller.
