OpenVMS Cluster Systems - OpenVMS Systems - HP
OpenVMS Cluster Systems - OpenVMS Systems - HP
OpenVMS Cluster Systems - OpenVMS Systems - HP
You also want an ePaper? Increase the reach of your titles
YUMPU automatically turns print PDFs into web optimized ePapers that Google loves.
Preparing a Shared Environment<br />
5.5 Defining and Accessing <strong>Cluster</strong>wide Logical Names<br />
5.5 Defining and Accessing <strong>Cluster</strong>wide Logical Names<br />
Initializing the clusterwide logical name database on a booting node requires<br />
sending a message to another node and having its CLUSTER_SERVER process<br />
reply with one or messages containing a description of the database. The<br />
CLUSTER_SERVER process on the booting node requests system services to<br />
create the equivalent names and tables. How long this initialization takes varies<br />
with conditions such as the size of the clusterwide logical name database, the<br />
speed of the cluster interconnect, and the responsiveness of the CLUSTER_<br />
SERVER process on the responding node.<br />
Until a booting node’s copy of the clusterwide logical name database is consistent<br />
with the logical name databases of the rest of the cluster, any attempt on<br />
the booting node to create or delete clusterwide names or tables is stalled<br />
transparently. Because translations are not stalled by default, any attempt<br />
to translate a clusterwide name before the database is consistent may fail<br />
or succeed, depending on timing. To stall a translation until the database is<br />
consistent, specify the F$TRNLNM CASE argument as INTERLOCKED.<br />
5.5.1 Defining <strong>Cluster</strong>wide Logical Names in SYSTARTUP_VMS.COM<br />
In general, system managers edit the SYLOGICALS.COM command procedure<br />
to define site-specific logical names that take effect at system startup. However,<br />
Compaq recommends that, if possible, clusterwide logical names be defined in the<br />
SYSTARTUP_VMS.COM command procedure instead with the exception of those<br />
logical names discussed in Section 5.5.2. The reason for defining clusterwide<br />
logical names in SYSTARTUP_VMS.COM is that SYSTARTUP_VMS.COM is run<br />
at a much later stage in the booting process than SYLOGICALS.COM.<br />
<strong>OpenVMS</strong> startup is single streamed and synchronous except for actions taken<br />
by created processes, such as the CLUSTER_SERVER process. Although the<br />
CLUSTER_SERVER process is created very early in startup, it is possible that<br />
when SYLOGICALS.COM is executed, the booting node’s copy of the clusterwide<br />
logical name database has not been fully initialized. In such a case, a clusterwide<br />
definition in SYLOGICALS.COM would stall startup and increase the time it<br />
takes for the system to become operational.<br />
<strong>OpenVMS</strong> will ensure that the clusterwide database has been initialized before<br />
SYSTARTUP_VMS.COM is executed.<br />
5.5.2 Defining Certain Logical Names in SYLOGICALS.COM<br />
To be effective, certain logical names, such as LMF$LICENSE, NET$PROXY,<br />
and VMS$OBJECTS must be defined earlier in startup than when SYSTARTUP_<br />
VMS.COM is invoked. Most such names are defined in SYLOGICALS.COM, with<br />
the exception of VMS$OBJECTS, which is defined in SYSECURITY.COM, and<br />
any names defined in SYCONFIG.COM.<br />
Although Compaq recommends defining clusterwide logical names in<br />
SYSTARTUP_VMS.COM, to define these names to be clusterwide, you must<br />
do so in SYLOGICALS.COM or SYSECURITY.COM. Note that doing this may<br />
increase startup time.<br />
Alternatively, you can take the traditional approach and define these names as<br />
systemwide logical names with the same definition on every node.<br />
5–12 Preparing a Shared Environment
Change language