Deployment Guide
Table Of Contents
- Dell EMC PowerVault MD3860f Series Storage Arrays Deployment Guide
- Introduction
- Hardware installation
- Planning the storage configuration
- Connecting the storage array
- Configuring Fibre Channel with Dell EMC MD Series storage arrays
- Configuring Fibre Channel on SAN attached storage arrays
- Other information you may need
- Installing supported Fibre Channel HBAs
- Using Fibre Channel switch zoning
- Cabling storage array
- SAN-attached cabling
- Cabling PowerVault MD3060e expansion enclosures
- Installing MD Storage Manager
- Post installation tasks
- Uninstalling MD Storage Manager
- Load balancing
- Appendix — Working with SFP modules and fiber optic cables
- Appendix — Hardware cabling best practices
- Getting help
Load balancing
Topics:
• Load balance policy
•
Setting load balance policies in Linux
• Setting load balance policies in VMware
Load balance policy
Multi-path drivers select the I/O path to a virtual disk through a specific RAID controller module. When the multi-path driver
receives a new I/O to process, the driver tries to find a path to the current RAID controller module that owns the virtual disk.
If the path to the current RAID controller module that owns the virtual disk cannot be found, the multi-path driver migrates the
virtual disk ownership to the secondary RAID controller module. When multiple paths to the RAID controller module that owns
the virtual disk exist, you can choose a load balance policy to determine which path is used to process I/O. Multiple options for
setting the load balance policies let you optimize I/O performance when mixed host interfaces are configured.
NOTE: For more information on Load Balance Policy, see your operating system’s manual and updates.
You can choose one of the following load balance policies to optimize I/O performance:
● Round robin
● Least queue depth
● Least path weight (Microsoft Windows operating systems only)
Round robin with subset
The round robin with subset I/O load balance policy routes I/O requests, in rotation, to each available data path to the RAID
controller module that owns the virtual disks. This policy treats all paths to the RAID controller module that owns the virtual
disk equally for I/O activity. Paths to the secondary RAID controller module are ignored until ownership changes. The basic
assumption for the round-robin policy is that the data paths are equal. With mixed host support, the data paths might have
different bandwidths or different data transfer speeds.
Least queue depth
The least queue depth policy is also known as the least I/Os or least requests policy. This policy routes the next I/O request to a
data path that has the least outstanding I/O requests queued. For this policy, an I/O request is simply a command in the queue.
The type of command or the number of blocks that are associated with the command are not considered.
The least queue depth policy treats large block requests and small block requests equally. The data path selected is one of the
paths in the path group of the RAID controller module that owns the virtual disk.
Least path weight
The least path weight policy assigns a weight factor to each data path to a virtual disk. An I/O request is routed to the path
with the lowest weight value to the RAID controller module that owns the virtual disk. If more than one data path to the virtual
disk has the same weight value, the round robin with subset path selection policy is used to route I/O requests between the
paths with the same weight value. The least path weight load balance policy is not supported on Linux operating systems.
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