How to migrate SRL Layout from Concatenated to Striped in Veritas Volume Replicator (VVR)

Description

This article describes the procedure and best practices for migrating the Storage Replicator Log (SRL) volume layout from concatenated to striped in a Veritas Volume Replicator (VVR) environment. Striping the SRL across multiple disks can significantly improve replication performance and I/O distribution, especially in environments with high write throughput.

This procedure was validated in a production environment with the following configuration: Below is a sample lab.

• Primary Server: server101
• Secondary Server: drserver203
• Diskgroup: testdg
• SRL Volume Name: srl
• SRL Size: 2 GB (4194304 blocks)
• Target Disks for Striping:
  • Primary: ibm_shark0_2, ibm_shark0_3
  • Secondary: hitachi_usp-v0_1510, hitachi_usp-v0_1151

Procedure

1. Pre-Change Checks

• Freeze the Service Groups if part of Infoscale Cluster.
• Confirm adequate free space on target disks.
• Backup current configuration:

           vxprint -ht > /var/tmp/vxprint-ht-$(date +%F)vxdg list > /var/tmp/vxdg-list-$(date +%F)

2. On Primary Server

1. Detach the RLINK:
   vxrlink -g testdg det server101_rlk
2. Stop the RVG:
   vxrvg -g testdg stop rvg
3. Disassociate the SRL:
   vxvol -g testdg dis srl
4. Remove the old SRL volume:
   vxedit -g testdg -rf rm srl
5. Create a new striped SRL volume:
   vxassist -g testdg make srl 4194304 layout=stripe stripeunit=64k
6. Start the new SRL volume:
   vxvol -g testdg start srl
7. Associate the new SRL with the RVG:
   vxvol -g testdg aslog rvg srl
8. Start the RVG:
   vxrvg -g testdg start rvg
9. Reattach the RLINK:
   vxrlink -g testdg -a att server101_rlk

3. On Secondary Server

1. Detach the RLINK:
   vxrlink -g testdg det drserver203_rlk
2. Stop the RVG:
   vxrvg -g testdg stop rvg
3. Disassociate the SRL:
   vxvol -g testdg dis srl
4. Stop the SRL volume:
   vxvol -g testdg stop srl
5. Remove the old SRL volume:
   vxedit -g testdg -rf rm srl
6. Create a new striped SRL volume:
   vxassist -g testdg make srl 4194304 layout=stripe stripeunit=64k
7. Start the new SRL volume:
   vxvol -g testdg start srl
8. Associate the new SRL with the RVG:
   vxvol -g testdg aslog rvg srl
9. Start the RVG:
   vxrvg -g testdg start rvg
10. Reattach the RLINK:
    vxrlink -g testdg att drserver203_rlk

4. Verification

Before Change (Concatenated SRL)

Sample output from vxprint -ht:

v  srl          rvg          ENABLED  ACTIVE   2.00g    SELECT    -        SRL

pl srl-01       srl          ENABLED  ACTIVE   2.00g    CONCAT    RW

sd ibm_shark0_2-02 srl-01    ibm_shark0_2 2.00g 2.00g   0/0.00    ibm_shark0_2 ENA

After Change (Striped SRL)

Sample output from vxprint -ht:

v  srl          rvg          ENABLED  ACTIVE   2.00g    SELECT    -        SRL

pl srl-01       srl          ENABLED  ACTIVE   2.00g    STRIPE    2/64.00k RW

sd ibm_shark0_2-02 srl-01    ibm_shark0_2 2.00g 1.00g   0/0.00    ibm_shark0_2 ENA

sd ibm_shark0_3-04 srl-01    ibm_shark0_3 2.00g 1.00g   1/0.00    ibm_shark0_3 ENA

Replication Status

• Replication resumed and healthy.
• Status:
  • Replication status: replicating (connected)
  • Data status: consistent, up-to-date

References

• How to remove an SRL from a VVR RVG, and then recreate it
• Best Practices for SRL Layout