Symptoms
A Consistency Group, (CG,) full sweep/initialization is progressing slowly if the protected production volume is more than 85% similar to volume in replica.
Various symptoms are found within the repliaction logs:
STATISTICS: name=pingerWaitingTimeForPonger GroupCopy(XXXXXXXX SiteUID(0xXXXXXXXXXXXX) 0)
(replicationLinkID=(kVolSlot=XXXXXXXX,srcCopyID=GlobalCopy(SiteUID(0xXXXXXXXXXXXX) 0) ,destCopyID=GlobalCopy(SiteUID(0xXXXXXXXXXXXX) 0) ),gridCopyID=0) 64 sec window: sec/secRate: 1.46e+02 % Sample Rate: 9.24e+00 samples/sec
STATISTICS: name=pingerWaitingTimeForPonger GroupCopy(XXXXXXXX SiteUID(0xXXXXXXXXXXXX) 0)
(replicationLinkID=(kVolSlot=XXXXXXXX ,srcCopyID=GlobalCopy(SiteUID(0xXXXXXXXXXXXX) 0) ,destCopyID=GlobalCopy(SiteUID(0xXXXXXXXXXXXX) 0) ),gridCopyID=0) 860 sec window: sec/secRate: 1.46e+02 % Sample Rate: 9.14e+00 samples/sec
STATISTICS: name=pingerSignaturesReduction GroupCopy(XXXXXXXX SiteUID(0xXXXXXXXXXXXX) 0)
(replicationLinkID=(kVolSlot=XXXXXXXX ,srcCopyID=GlobalCopy(SiteUID(0xXXXXXXXXXXXX) 0) ,destCopyID=GlobalCopy(SiteUID(0xXXXXXXXXXXXX) 0) ),gridCopyID=0) 564 sec window: Rate: 7.30e+01 blocks/sec Average: 4.72e-04 blocks Sample Rate: 1.55e+05 samples/sec
Cause
RecoverPoint and RecoverPoint for Virtual machines uses a Signature Exchange Mechanism, (SEM,) to compare the production volume information to the replica volume information.
Signature exchange works by reading the same intervals from the production and the replica copies and comparing their CRCs, (Cyclic Redundancy Checks). If the CRCs are equal, the data isn t being sent, however if the CRCs aren t equal, the actual data is being sent.
This signature exchange calculation consumes more than 40% of the initialization time. Without this, the initialization will take approximately twice as long, as long as the WAN or Fiber Channel connectivity is sufficient.
Resolution
Workaround:
Change the tweak t_bExchangeAllowed to false, followed by a RecoverPoint Appliance, (RPA,) reboot of the RPA handling the CG traffic. Ensure to reboot the primary RPA if the CG is a Distributed Consistency Group.
The t_bExchangeAllowed tweak controls the exchange of signatures during the init process. When set to false, instead of comparing copies to see if the production data differs from the replica data and only sending changed data, all data is sent to the replica.
This can be changed via the boxmgmt menu:
[2] Setup
[8] Advanced options
[3] Appliance config params
[3] Change appliance config param value
Enter tweak_param name: t_bExchangeAllowed
Enter tweak_param value (Default 'true'): false
Enter your name: <enter name>
To reboot, go back to the Main Menu
[M] Main Menu
[5] Shutdown / Reboot operations
[1] Reboot RPA
Please note, this will increase WAN traffic utilization.
Resolution:
EMC Engineering is currently investigating this issue. A permanent fix is still in progress. Contact the Dell EMC Customer Support Center or your service representative for assistance and reference this solution ID.
Affected Products
RecoverPoint
Products
RecoverPoint, RecoverPoint CL, RecoverPoint EX, RecoverPoint for Virtual Machines, RecoverPoint SE