11
Recommended Multipath Settings
For Linux environments, it is recommended to change from the default settings for multipathing. For
heavily loaded I/O environments, such as with the VMA SAN Gateway, it has proven to be more
efficient to use the „tur‟ checker method instead of the „readsector0‟ or „directio‟ alternatives to check
the health of lunpaths. An example multipath setting would be:
devices {
device {
vendor "VIOLIN "
product "SAN ARRAY "
path_grouping_policy multibus
path_checker tur
getuid_callout "/sbin/scsi_id -g -u -s /block/%n"
path_selector "round-robin 0"
failback immediate
rr_weight uniform
rr_min_io 20
}
}
The „rr_min_io‟ value denotes the minimum number of I/O operations to send down the current
lunpath before selecting the next lunpath. A lower value than typically used with standard rotational
media storage array controllers has proven better to keep all lunpaths busy. This value could be
further tuned for your specific environment based on workload and number of lunpaths.
Queue-Depth Settings for SLES 11 SP1 and RHEL 5.7
The HBA drivers used with Linux have default LUN level queue depth values of 30 or 32 depending
upon the HBA vendor. In many cases this default value will provide good results. However in cases
where a large number of LUNs are used with a large number of server FC initiator ports, the resulting
I/O load could cause Queue-Full conditions and I/O retries leading to non-optimal performance.
For optimal I/O performance use, the following equation to determine the LUN queue depth settings
for the FC HBA driver:
LUN Queue Depth value =
(( <# gateway FC target ports> * 1024) / <# of server FC initiator ports> / <# of LUNs>)
If the resulting LUN Queue Depth value is greater than the HBA driver default (usually 30 or 32), then
use driver default setting.
Windows
Microsoft Windows Server 2008 R2 and Windows 2008 R2 SP1 releases have been validated on
the DL980 G7 server with the HP VMA SAN Gateway and connected VMA-series Memory Arrays. It
is recommended to apply all the latest patches and MPIO QFEs before connecting your system to the
VMA SAN Gateway appliance. Some additional limitations and considerations for Windows Server
2008 R2 and R2 SP1 environments are presented in the following subsections.
Recommended MPIO Changes:
It is recommended to ensure that MPIO is enabled and correctly configuring MPIO for LUNs presented
by the VMA SAN Gateway. If MPIO is not already enabled and active on the server, perform the
following steps to activate it:
1. Click:
START -> Administrative Tools -> Server Manager -> Features.
2. Click Add Features.
(134 Seiten)
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