3.7.0 HP StorageWorks HP Scalable NAS File Serving Software upgrade guide HP Scalable NAS for Linux (AG513-96005, October 2009)

I/O scheduler policies
The Linux I/O schedulers (also called elevators) attempt to sort and issue disk I/O
requests according to specific priority policies. Testing has shown that the deadline
policy results in the best performance for the PSFS filesystem.
The deadline policy is the default in the SLES10 kernel. For RHEL5, the default
policy is cfq. In the HP RHEL5 binary kernels and kernel sources provided by HP,
the I/O scheduler policy has been set to deadline.
For best performance, HP recommends that you do not change the deadline policy
for the I/O schedulers.
Upgrade considerations
Several changes in HP Scalable NAS File Serving Software 3.7.0 affect the upgrade
procedure. Be sure to review the following information before starting the upgrade.
Upgrade all servers as quickly as possible
It is important to upgrade all nodes in the cluster within a short time frame. We do
not recommend running the cluster for an extended period of time with only some of
the nodes upgraded to 3.7.0. This release introduces a new configuration data
repository and a new logging facility that do not become fully functional until all
nodes are upgraded. If the cluster is only partially upgraded, alerts raised by nodes
running 3.7.0 will be improperly logged by nodes running an earlier Matrix Server
version.
User and group IDs
When you restore users and groups after upgrading the operating system, be sure
that the user and group IDs on the new operating system match those used on
RHEL4/SLES9. This is important because the users/groups must have the same IDs
to be able to access their files and directories on the PSFS filesystem. For example,
if user1 had uid 500 before the upgrade but is assigned uid 501 after the upgrade,
the user will no longer have the correct directory permissions on the PSFS filesystem.
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