Trying To Answer The Initial Questions; How Many Hard Disks Should Be Integrated Into The Disk Array - ICP RS Series User Manual

ICPCON allows you to limit the hard disk size for this Host Drive. This becomes interesting
when you configure disk arrays and you want to make sure that future drives you want to
only had 8681 MB. ICPCON couldn't accept it. To avoid this occurring, you could limit the
capacity of each drive to 8000 MB. Any new 9 GB drive must have at least this capacity.
Press ENTER
The new Host Drive is created. It's status is still build, since the ICP Controller creates the
parity information on all drives.
When leaving ICPCON, a progress information informs you about the Estimated time for
this build process and the time it already runs.
Upon successful completion of this process the status of this RAID 5 Disk Array changes
into ready, i.e., the data is fully redundant.
In case of a drive failure, the ICP Controller automatically starts the Hot Fix Drive and
builds it into the Disk Array. The status of the Disk Array would be rebuild and finally ready,
again.
C.6 Trying to Answer The Initial Questions
C.6.1 How Many Hard Disks Should be Integrated Into the Disk Array ?
To answer this question let us have a look at the delimiting parameters, that is, the maxi-
mum and minimum number of drives. The maximum number of physical drives in a disk
array is determined by the number of physical drives the ICP Controller can. In this context,
we cannot analyze the many various factors which influence the decision of whether to in-
tegrate all Host Drives into one single RAID Host Drive, or rather create a number of
smaller RAID Host Drives instead. The minimum number of necessary hard disks depends
on the RAID level you wish to realize.
RAID Level
RAID 0
RAID 1
RAID 4
RAID 5
RAID 10
The desired usable disk space of the disk array as well as the following two issues have a
direct impact on the number of physical hard disks needed.
66
Type of Disk Array
data striping
disk mirroring
data striping with parity drive
data striping with striped parity
data striping and mirroring
bring into the disk array (for replace-
ment or online capacity reasons) fit.
It would be bad luck if the new drive
Minimum number of hard disks
2
2
3
3
4