HP StorageWorks Command View SDM Installation and User Guide (T1086-96023, February 2005)

170 Command Line User Interface
RAID 1+0 Allocation (1.05
release)
RAID 1+0 Capacity (absolute)
(prior to 1.05)
ARRAY The number of logical blocks in the array that are stored
using the RAID 1+0 storage method. It is a sum of the
RAID 1+0 Allocation metrics from each configured LUN.
Usage
RAID 1+0 provides better random write performance than
RAID 5 DP. The more data stored in RAID 1+0 as
compared to RAID 5 DP, the better the random write
performance that can be achieved. AutoRAID policies will
migrate the write working set into RAID 1+0 for better
random write performance. If better random write
performance is needed in an AutoRAID configuration,
adding more disks to the array may provide enough space
to fit the write working set into RAID 1+0 providing better
random write performance. This metric can be compared
with the RAID 5 DP Allocation metric to determine the
overall distribution of data across the two storage
methods. Space that has been allocated to configured
LUN's but has not been written to yet will not be counted in
either the RAID 1+0 Allocation or the RAID 5 DP
Allocation metrics. The sum of these two metrics can be
compared to the total capacity allocated to configured
LUN's to determine how “full” the array is.
RAID 1+0 to RAID 1+0
Relocations Spawned by
MakeSpace
OPAQUE The number of clusters that were relocated by the make
space policy from RAID 1+0 to RAID 1+0 storage.
Usage
The RAID 1+0 storage areas can become filled with holes
of empty space similar to the RAID 5 DP storage areas
(reference the “RAID 5 DP to RAID 5 DP Relocations
Spawned by MakeSpace” metric). The RAID 1+0 holes do
not need to be garbage collected to turn them into usable
free space. Data from the write cache can be posted
directly into RAID 1+0 holes. Therefore, RAID 1+0 to RAID
1+0 relocations are not ever expected to be spawned by
the make space policy. This metric will always have the
value zero except under unforeseen circumstances.
Table 12 Performance Metrics (Continued)
Metric Categories Description/Usage