31 error handling, Timeouts for remote copy failure, Timeouts and transient network problems – HP 3PAR Operating System Software User Manual
Page 207: Failure of a single link
31 Error Handling
See:
For more information on:
“Timeouts for Remote Copy Failure” (page 207)
The timeout periods per type of failure and volume group
mode
“Failure of a Single Link” (page 207)
The effect of one link failing
“Failure of All Links” (page 208)
What happens when all links in a Remote Copy pair fail
“Failure of a Storage System” (page 209)
How Remote Copy handles system failures
Different types of write errors
Different types of read errors
Additional Information:
“Recovering from Disaster” (page 102)
Timeouts for Remote Copy Failure
Remote Copy uses two main timeouts to send alerts about link and system failures. The timeout
period depends on the mode of the volume group.
Timeout Period: Periodic
Timeout Period: Sync
Function
Timeout
25
15
Remote Copy declares an
unresponsive link down.
link heartbeat timeout
200
15
Remote Copy declares a
target system down after all
links have gone down.
target timeout
Remote Copy uses low timeout values for synchronous volume groups to ensure that Remote Copy
stops replication before the host I/O times out.
Timeouts and Transient Network Problems
If Remote Copy is using a network that has transient problems, Remote Copy might display repeated
link failure alerts and even stop all synchronous volume groups.
If Remote Copy uses asynchronous periodic volume groups, the longer timeout values allow Remote
Copy to continue functioning even if there are transient network problems.
Failure of a Single Link
When a link between storage systems fails, the system issues an alert on each system as soon as
it detects the link failure.
If at least one other link between the two systems remains active, Remote Copy remains in normal
operation and sends all data through the remaining link(s).
The system might experience a slight reduction in throughput (bandwidth), but a single link failure
in a multiple-link Remote Copy pair does not incur any errors under normal operating conditions
other than the link failure itself.
Timeouts for Remote Copy Failure 207