Product manual

CDA 7 5630 Product Manual
5-14 77 A1 69UP Rev00
5.3.3 Cache Error Correction and Error Verification
The disk directors use idle time to periodically read cache, correct single-bit errors
(one hard and one soft), and write the corrected data back to cache. This process is
called “error verification.” When the directors detect an uncorrectable error in
cache, CDA 7 reads the data from disk and takes the defective cache memory block
offline until an Bull Customer Engineer can repair it. Error verification maximizes
data availability by significantly reducing the probability of encountering an
uncorrectable error by preventing bit errors from accumulating in cache.
5.4 Data Protection Guidelines
The CDA 7 data protection options ensure a higher level of data protection,
recoverability, and availability than the standard CDA 7 availability and reliability
features. The following options can be purchased separately and implemented into
the CDA 7 operation:
• Mirroring
• CDA 7 Remote Data Facility (SRDF)
The following table describes the CDA 7 data protection options. You can choose
one or more of these options to match your critical data protection requirements.
Table 5-1. Data Protection Options
Data Protection Option Description
Mirroring (RAID-1) Provides the highest level of performance and
availability for all mission critical and business
critical applications by maintaining a duplicate
copy of a volume on two disk devices.
For more information, refer to Mirroring.
CDA 7 Remote Data
Facility (SRDF)
Provides a disaster recovery solution by
maintaining a mirror image of data in two
CDA 7 systems which can be in physically
separate locations.
For more information, refer to SRDF.