请教几个关于DS5000配置及存储基本概念的问题。

Question

Host zone 1: HBA_1 is in a zone with DS5000 controller A0.
Host zone 2: HBA_1 is in a zone with DS5000 controller B0.
Host zone 3: HBA_2 is in a zone with DS5000 controller A1.
Host zone 4: HBA_2 is in a zone with DS5000 controller B1.
1，上面这样的配置，主机每个LUN有4条path。MPIO+SDDPCM应该是可以实现load balance的？
2，像以上这种配置，hdisk必须要chdev -l hdisk2 -a reserve_policy=no_reserve -a algorithm=round_robin这样设置吗？使用默认的reserve_policy=single_path，algorithm=failover会有什么问题呢？
3，没太明白round_robin和load_balance的区别？
round_robin: Distributes the I/O across all enabled paths. The path priority is determined
by the path priority attribute value. If a path becomes marked failed or disabled, it is no
longer used for sending I/O. The priority of the remaining paths is then recalculated to
determine the percentage of I/O that must be sent down each path. If all paths have the
same value, then the I/O is then equally distributed across all enabled paths.

load_balance: (SDDPCM only) This algorithm is based on the existing load balancing
algorithm, but it also uses the incorporated I/O statistics on each target port to which the
host is connected. You can use this algorithm for SAN configurations where I/O throughput
is unbalanced on the storage targets.

4，另外配置DS5000的时候只发现了dac设备，没有现dar了？