24-13
User Guide for Cisco Security MARS Local Controller
78-17020-01
Chapter 24 System Maintenance
Hardware Maintenance Tasks—MARS 100, 100E, 200, GCM, and GC
The MARS RAID controller cards operate the hard drives in a RAID 10 configuration, also called RAID
1+0 because it combines the data handling techniques of RAID 1 and RAID 0. For additional
information on RAID concepts and terminology, access the following URL:
http://en.wikipedia.org/wiki/RAID
RAID 0 Data Striping
In a MARS RAID 10 configuration, half the total number of drives are arrayed as a single logical drive,
wherein a data block is distributed across all of the physical drives in the logical drive using RAID 0
striping techniques. Data striping results in better performance for a data intensive application such as
MARS, because hard drive random access times are minimized when data is read and written
simultaneously from more than one physical hard drive.
RAID 1 Mirroring and Subunits
The remaining drives in the MARS RAID 10 array mirror the RAID 0 virtual drive. Each physical drive
in the RAID 0 array is mirrored by an identical physical drive using RAID 1 techniques. Data written to
one of the drives within the RAID 0 array is simultaneously written to its dedicated RAID 1 partner,
thereby providing fault tolerance through data redundancy.
A RAID 1 pair is termed a subunit. For example, an 8-drive Local Controller 200 has 4 RAID 1 subunits
(8 drives in total), a 6-drive Local Controller 100 has 3 subunits (6 drives in total).
A subunit always comprises the same two hard drive slots. For instance, a MARS 110 or GC2 will always
have the same pairings in a subunit, Slots 0 and 1, physical hard drive pairings
Rebuilding a Degraded Array
Either drive in a subunit can serve in place of its partner should either drive become degraded
(unavailable, physically inoperative, or data corrupted). A physical drive degraded but still physically
operative can be rebuilt from the data of its undegraded partner and rejoin the array. An inoperative
physical drive can be replaced with an operative one which is then rebuilt to join the array.
When any physical drive of the RAID 10 array is degraded, the entire array is considered degraded.
While the array still functions, it is not working to its optimal throughput or redundancy capacity.
In a degraded RAID 10 array, data destined for degraded physical drives are written to available space
on other subunits until the degraded drives are rebuilt or replaced. Degraded drives are rebuilt in
sequence, one rebuilding process must complete before the next process can begin. Between 90 minutes
and 2 hours are required to rebuild a MARS subunit. The more data to rebuild, the more time is
consumed.
Hotswapping and Field-Replaceable Hard Drives
A physical hard drive can be hotswapped, that is, replaced without rebooting the MARS appliance. Use
the
hotswap
CLI command before removing or inserting a new hard drive.
Note
To match original performance, hotswapped hard drives should be the same make, model and size as the
original hard drives.
RAID Procedures for MARS Appliances 100, 100E, 200, GCM, and GC
This section pertains only to the MARS 100, 100E, 200, GCM, and GC appliances.
Содержание CS-MARS-20-K9 - Security MARS 20
Страница 20: ...Contents xx User Guide for Cisco Security MARS Local Controller 78 17020 01 ...
Страница 356: ...17 16 User Guide for Cisco Security MARS Local Controller 78 17020 01 Chapter 17 Network Summary Summary Page ...
Страница 420: ...20 28 User Guide for Cisco Security MARS Local Controller 78 17020 01 Chapter 20 Queries and Reports Reports ...
Страница 580: ...Glossary GL 4 User Guide for Cisco Security MARS Local Controller 78 17020 01 ...