Storage Management Overview
52
NAS 2000s Administration Guide
This technology allows the safe deployment of large capacity disk drives and the creation of
very large storage volumes without expensive overhead to protect business critical data. This
technology provides more flexibility in responding to drive failures without the fear of costly
server downtime.
Advance Data Guarding protects against multiple disk failures, while requiring the capacity of
two drives in an array of up to 56 disk drives to be set aside for dual sets of distributed parity
data. It provides data protection greater than RAID 5, and also has the capacity utilization
efficiency similar to RAID 5.
Advantages
■
High read performance
■
High data availability-any two drives can fail without loss of critical data
Disadvantage
■
Relatively low write performance (lower than RAID 5), due to the need for two sets of
parity data
The table below summarizes the important features of the different kinds of RAID supported
by the Smart Array controllers. The decision chart in the following table may help determine
which option is best for different situations.
Table 3: Summary of RAID Methods
RAID 0
Striping (no
fault
tolerance)
RAID 1+0
Mirroring
RAID 5
Distributed
Data
Guarding
RAID ADG
Advanced
Data
Guarding
Usable drive space
formula
n
n/2
(n-1)/n
(n-2)/n
Minimum number of
hard drives
1
2
3
4
Maximum number of
hard drives
N/A
N/A
14
56
Tolerant of single hard
drive failure?
No
Yes
Yes
Yes
Tolerant of multiple
simultaneous hard drive
failure?
No
For RAID
1+0, if the
failed drives
are not
mirrored to
each other
No
Yes
(two drives
can fail)
Содержание 345646-001 - StorageWorks NAS 2000s External Storage Server
Страница 16: ...About this Guide 16 NAS 2000s Administration Guide ...
Страница 56: ...Storage Management Overview 56 NAS 2000s Administration Guide ...
Страница 80: ...Disk Management 80 NAS 2000s Administration Guide ...
Страница 93: ...Shadow Copies 93 NAS 2000s Administration Guide Figure 46 Accessing shadow copies from My Computer ...
Страница 110: ...User and Group Management 110 NAS 2000s Administration Guide ...
Страница 146: ...Folder Printer and Share Management 146 NAS 2000s Administration Guide ...
Страница 151: ...Microsoft Services for NFS 151 NAS 2000s Administration Guide Figure 83 Server for NFS screen Server Settings tab ...
Страница 186: ...NetWare File System Management 186 NAS 2000s Administration Guide ...
Страница 200: ...Index 200 NAS 2000s Administration Guide ...