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Data capacity of VA7100

Mad_1
Regular Advisor

Data capacity of VA7100

I am using VA7100, There are totally 15 x 36.4GB disks installed in the VA7100. In the output of armdsp, there are some figures shows the size of the VA7100, however, some figures are quite confused, does anyone has experience in using VA7100 and know what those figures mean? Actually, what I most concern is how many usable capacity I can use.

Below is the output of armdsp

=================================

Disk at M/D1:
Vendor ID:____________________________HP 36.4G
Data Capacity:________________________33.378 GB (70000000 blocks
:
:
:

Redundancy Group:_____________________1
Total Disks:________________________15
Total Physical Size:________________500.679 GB
Allocated to Regular LUNs:__________174.048 GB
Allocated as Business Copies:_______0 bytes
Used as Active Hot Spare:___________66.757 GB
Used for Redundancy:________________187.035 GB
Unallocated (Available for LUNs):___72.837 GB

=======================================

As shown, the 36.4 GB disk only has 33.378 GB data capacity, where is other 3.1 GB gone?

Thanks

 

 

P.S. This thread has been moevd from General to Disk array. - Hp Forum Moderator

3 REPLIES
James A. Donovan
Honored Contributor

Re: Data capacity of VA7100

36.4 GB is the raw, unformatted capacity of the physical disk. The act of formatting (i.e. readying the disk for use by an operating system) always reduces the amount of useable disk space.

You are effectively using 2 of your disks as hot spares 33.378*2=66.757, leaving you 13 useable drives. You have a very high amunt of disk being used for redundancy, so I assume that you are running the array in RAID10 mode, not AUTORAID.

Right now, you can only allocate up to 72.837 GB more disk space, before you run out of room.
Remember, wherever you go, there you are...
Joshua Scott
Honored Contributor

Re: Data capacity of VA7100

This is a result of a couple of things.
First, the VA uses 520 byte blocks instead of 512 bytes. This causes about 1.5% decrease in available size.

Also, "36.4G" refers to 36.4 billion bytes, which is a marketing ploy to make the drive seem larger. a gigabyte is technically 1024MB, a MB is 1024KB, a KB is 1024Bytes.

Calculated out:
36.4Billion =
35,546MB =
34,713,745KB =
33,900,141,000Bytes.
subtracting the 1.5% loss from block size:
33,391,639,000Bytes
or
33.391GB

which is fairly close to the actual figure of 33.378GB. The minor difference is due to manufacturing tolerances.

(Head spinning yet?)
Josh
What are the chances...
Sijesh
Advisor

Re: Data capacity of VA7100

VA 7100 will have 2 'map' drives where it keeps the maps to the physical data blocks.

Arrey allocates space for map drive from 2 disks(not full disk space) while fromatting.

Sijesh