Cisco Headend System Release 2.7 Installation Guide
Database Fragmentation, Database Used Capacity, and the Doctor Report
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An Explanation of Database Used Capacity
Prior to version 1.1 of DNCS Utilities, when system operators used the dncsDbData
utility to defragment the database, related data was reloaded contiguously into the
database, but no additional space was allocated to the emm table. The database was
then subject to fragmentation again as the emm table grew.
utility to defragment the database, related data was reloaded contiguously into the
database, but no additional space was allocated to the emm table. The database was
then subject to fragmentation again as the emm table grew.
Beginning with version 1.1 of DNCS Utilities however, the reload function of the
dncsDbData utility preallocates a significant amount of space to the emm table. By
preallocating space to the emm table, the table can grow substantially without it
becoming fragmented across the hard drive as it grows. The Doctor Report considers
this preallocated space as used, even though it may consist largely of empty space.
Therefore, Doctor Reports generated after defragmenting the database are likely to
show a significant increase in the percentage of database used capacity.
dncsDbData utility preallocates a significant amount of space to the emm table. By
preallocating space to the emm table, the table can grow substantially without it
becoming fragmented across the hard drive as it grows. The Doctor Report considers
this preallocated space as used, even though it may consist largely of empty space.
Therefore, Doctor Reports generated after defragmenting the database are likely to
show a significant increase in the percentage of database used capacity.
Note: The amount of space preallocated to the emm table is based upon the
following factors:
following factors:
The number of database spaces configured on the system
The hardware platform of the DNCS
The number of disks assigned to the database
Conclusion
System operators of sites that see the condition described in this section, after
defragmenting the database, can safely ignore this condition.
defragmenting the database, can safely ignore this condition.