HP P6000 SmartStart Storage Software - Manual (Page 30)

See also Disk group capacity , Storage system and storage network capacity and Virtual disk
capacity .
Storage capacity FAQ
•
Does the HP P6000 Command View GUI show capacities as decimal-based or binary-based
values?
Binary-based. HP P6000 Command View displays all physical and virtual disk capacities as
the decimal equivalent of the binary-based values, where the measures MB, GB, and TB have
the following values:
MB (megabyte) = 1,048,576 bytes (2
20
)
GB (gigabyte) = 1,073,741,824 bytes (2
30
), or 1024 MB
TB (terabyte) = 1,099,511,627,776 bytes (2
40
), 1024 GB, or 1,048,576 MB
•
Why are disk capacities shown in the GUI smaller than on physical disk labels or specs?
The smaller capacities are primarily due to:
◦ HP P6000 Command View shows formatted capacity, but physical disk drive labels and
specs indicate raw, unformatted capacity. Formatted capacity is always less than raw,
unformatted capacity.
◦ HP P6000 Command View shows binary-based capacity measures, but physical disk
labels show decimal-based measures.
For example, if the label on a physical disk shows the decimal value 500 GB, then the
equivalent binary value is 456 GB (derived by dividing 500,000,000,000 bytes by
1,073,741,824 bytes per binary MB). The binary value looks smaller, but represent the
same number of bytes as the decimal value.
•
Are capacities on physical disk labels and specs decimal-based or binary-based values?
Decimal-based. Disk drive manufacturers show capacities as decimal values, where the
measures MB, GB, and TB have the following values:
MB (megabyte) = 1,000,000 bytes (10
6
)
1 GB (gigabyte) = 1,000,000,000 bytes (10
9
), or 1,000 MB
1 TB (terabyte) = 1,000,000,000,000 bytes (10
12
), 1,000 GB, or 1,000,000 MB
•
Why do the available capacities for disk groups not add up to the available capacity for the
storage system?
The available capacity of individual disk groups is calculated using different methods than
those used to calculate the available capacity for a storage system. Differences in these values
is expected behavior and does not indicate a problem.
Storage system capacity
HP P6000 Command View uses the following capacity-related terms for HP P6000 storage systems
and HP P6000 storage networks. Capacity measures of MB, GB and TB are binary values. See
Storage capacity FAQ
•
Total capacity. The storage space that is currently usable in an HP P6000 storage system, or
P6000 storage network.
This includes space in disk groups that is allocated to existing virtual disks, plus unallocated
space in disk groups that could be used to create new virtual disks or increase the size of
30 HP P6000 SmartStart concepts