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— much better than single disk
— slightly better than single disk
RAID
Levels
Cost
0
1
0 + 1
5
3.7 Other Facts on RAID and the SPARCstorage Array
Refer to Table 3-1 for to determine which RAID level best suits your needs.
Table 3-1
Comparisons of RAID Levels
— equal to single disk
Data transfer capacity
Data
Reliability
Writing Data
•
You can use any combination of independent disks or disks using RAID
levels 0, 1, 0 + 1, or 5 in the same array.
•
RAID groups may even span multiple arrays.
•
Optional hot spares are automatically swapped in to replace any failed disk
in a RAID 0 + 1 or 1 group without human intervention. Hot spares are
extra disk drives in the array that are powered up and ready to use. If a
drive in a RAID 0 + 1 or 1 group fails, the Volume Manager detects the
failure and automatically rebuilds the data from the failed drive onto a hot
spare drive.
•
There can be one or more hot spares per array. A hot spare drive can be tied
to one or more particular drives, one or more particular RAID groups, or
may be designated as a spare for any drive in any RAID group.
•
The combination of hot spares with warm pluggability provides new levels
of high availability and administrative flexibility. Hot spares allow
maintenance to be deferred for long periods of time and warm pluggability
means that the array downtime is very short when a failed drive is
eventually changed.
•
Since RAID is not ideal for many situations, the SPARCstorage Array allows
you to configure disk drives as regular, independent disks, rather than
forcing you to use RAID.
Software Configurations
— slightly worse than single disk
— much worse than single disk
Reading Data
Write
3
I/O Rate
Read
3-7
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