Hardware manual

Group Administration Group members
6–12
on the functional control module uses write-through mode. If you disable this policy (the default), the cache on
the functioning control module uses write-back mode.
• Use write-through mode if battery charge is below tolerance – Also
called low-battery-safe mode, if you enable
this policy (the default) on a member with a single control module, the cache uses write-through mode if the
charge on the cache battery is low.
If you enable this policy on a member w
ith dual control modules, but do not enable the single-controller-safe
policy, the active control module cache uses write-back mode if its cache battery has an adequate charge, but
the secondary control module’s cache battery has a low battery charge. If you enable the low-battery-safe
policy and the single-controller-safe policy, the active control module cache uses write-through mode if the
battery charge on either control module is low.
If you disable the low-battery-safe policy (not recommended), a ca
che use
s write-back mode, regardless of
cache battery charge.
To change the write cache policies, see Modifying write cache policies.
Modifying write cache policies
Recommendation: Dell recommends that you keep the default write cache policy settings for the best
performance and availability:
• Do not select (disable)
Use write-through mode if only one controller is
functional
.
• Select (enable) Use write-through mode if battery charge is below
tolerance
.
1. Click
Group, then expand Members, then select the member name, and then click the Controllers tab to
display the Member Controllers window
.
2. In the Memory Cache panel, select or deselect the cache mode policies.
3. Click Save all changes (Control+S).
About member firmware
Each control module you install in a group member must be running the same version of the PS Series firmware.
Firmware is stored on a compact flash card or a MicroSD card on each control module.
Recommendation: De
ll recommends that you always run the latest firmware to take advantage of new features
and fixes.
Dell recommends that all group members run the same firmware version. If you are
adding a
new array to a group, update the group to the latest firmware before adding the new member.
You can upgrade member firmware to a higher version or do
wngrade member firmware to a lower version.
There are two methods for updating firmware:
•
update command – See the CLI Reference manual.
• Group Manager GUI – See Updating member firmware.