How Do I Verify Data Consistency Between the Source and Target Servers?
SMS consistency verification allows you to verify data consistency before and after the migration. You can enable this function when you start an incremental synchronization.
Precautions
- Before enabling this function, you are advised to stop services (and databases if any) on the source server. If they are not stopped, data on the source server keeps changing, which will affect the consistency.
It is normal for some directories on the source and target servers to have slight differences. For instance, there are directories on the source server where data is always changing, such as the directory where SMS-Agent was installed and the /var/log directory where stores system logs.
- The time required for consistency verification depends on the number and size of files to be verified. If consistency verification takes a long time during the final incremental synchronization, the time required for service cutover will also increase. Evaluate the impact on your services.
- Consistency verification occupies significant source disk I/O resources. Evaluate the potential impacts on your source services.
Constraints
- Consistency verification does not apply to migration scenarios where disks or partitions are adjusted. In this case, directories and paths on the source and target servers are not perfectly mapped to each other.
- It is not applicable to verification of cross-file system files or shared folders.
- To ensure your services can run normally on the source server, a maximum of 100,000 files can be verified in a single directory.
- To prevent excessive memory usage, only files whose paths do not exceed 1024 bytes are verified.
Enabling Consistency Verification
- Open the Sync Incremental Data dialog box by referring to section Synchronizing Incremental Data.
- Enable Verify Consistency and correctly enter the directories for which data consistency is to be verified. If the entered directories are incorrect or empty, 0 will be displayed for these directories in the verification results.
- The larger the amount of data to be verified, the longer the consistency verification goes on. You are advised to verify only key directories.
- The following directories will be excluded from consistency verification by default:
- /, /etc, /dev, /sys, /usr, /boot, and /run in Linux
- Root directories of partitions in Windows, for example, C:\ and D:\.
- Select a verification method.
- Quick verification: compares the file size and last modification time.
- CRC verification: compares CRC64 checksums. This method scans file content in binary mode, which occupies a large amount of disk I/O resources and takes a long time but is more accurate.
- (Optional) Enable Verify Inconsistencies to verify files that were verified to be inconsistent in the previous verification. This option can only be enabled after at least one consistency verification is complete.
- Click Yes to synchronize incremental data and verify consistency. After the synchronization and verification are complete, you can view the verification results by referring to Viewing Verification Results.
Disabling Consistency Verification
If you want to disable consistency verification after the incremental synchronization starts, perform the following steps:
- Choose More > Pause in the Operation column to pause the synchronization task.
- Click Start in the Operation column.
- In the displayed dialog box, disable Verify Consistency and click Yes.
Viewing Verification Results
To view the data consistency verification results, choose More > Manage Migration Settings > View Verification Results in the Operation column.
If 0 is displayed in the Files Verified column, it means the specified directory could not be found or is empty.
All files verified to be inconsistent are recorded in the log file sms_cmp_result.log in the SMS-Agent installation directory (*/SmsAgent/agent/Logs/ on Linux and C://SMS-Agent-Py*/Logs on Windows) on the source server.
Verification Time Estimation
The following table lists the verification time tested on servers where only the migration process runs but is for reference only.
OS |
Specifications |
Disk Performance |
Verification Time (per 100 GB) |
---|---|---|---|
Windows |
2 vCPUs and 4 GB of memory |
5,000 IOPS/150 MB/s |
About 17 minutes |
Linux |
2 vCPUs and 4 GB of memory |
5,000 IOPS/150 MB/s |
About 13 minutes |
Product Consultation FAQs
- Can I Migrate Physical Servers and VMs from Other Clouds to Huawei Cloud Using SMS?
- Can I Migrate ECSs from Huawei Cloud to On-Premises Environments or Other Clouds Using SMS?
- Can I Ask Huawei Cloud Technical Support to Help Me Migrate Services?
- Does SMS Support Resumable Data Transfer?
- How Do I Migrate an ECS from One Account to Another?
- How Do I Migrate an ECS from One Region to Another Using SMS?
- Will My Services on the Source Server Be Interrupted During Migration?
- How Do I Create an AK/SK Pair for a Huawei Cloud Account?
- How Do I Create an AK/SK Pair for an IAM User?
- How Do I Migrate a Linux Source Server as a Non-root User?
- What Information Does SMS Collect About Source Servers?
- How Do I Select a Target Server?
- How Do I Create an ECS?
- What Is the Block-Level Migration?
- What are Valid Data Blocks?
- How Does Migration Using SMS Differ from Migration Using IMS?
- Why Is the OS Name of the Target ECS Displayed on the ECS Console Different from That of the Source Server?
- How Do I Determine Whether a Migration Is Complete?
- Can I Migrate Only Some Services on the Source Server?
- Can the Target Server Run a Different Type of OS from the Source Server?
- What Determines the Specifications of a Target Server?
- Which Download Option Should I Choose When I Download the Windows Agent?
- Can I Migrate a Source Server If There Is No Corresponding Image Available on Huawei Cloud?
- How Does SMS Differ from IMS in the Migration Scenario?
- How Do I Display the OS Name of a Target Server on the ECS Console?
- What Are the Snapshots of a Target Server Used for?
- In a Linux File-Level Migration, How Do I Exclude Directories from Migration and Synchronization?
- Will an Incremental Synchronization Overwrite Existing Data on a Launched Target Server?
- How Do I Create a Target Server that Meets the SMS Requirements?
- Can SMS Migrate Self-built Databases, Big Data Services, or Websites Deployed on a Source Server?
- Can the AK/SK of a Federated User (Virtual IAM User) Be Used for Authentication During the SMS-Agent Startup?
- How Do I Synchronize Files in Specific Directories After a Linux File-Level Migration Is Complete?
- Will the Migration Be Affected If the SSH Service Does Not Use Default Port 22 on the Source Server?
- How Do I Obtain the SMS Domain Name?
- How Many Resources Will Be Used for a Linux Block-Level Migration?
- How Do I Configure Data Compression for a Linux Block-Level Migration?
- Do I Need to Activate My Windows OS and Paid Software After the Migration?
- Why Does the Target Server Not Synchronize the Clocks on the Source Server?
- How Do I Set the Number of Concurrent Processes for Linux File-Level Migrations?
- Which Directories Are Not Synchronized by Default During Incremental Synchronization on a Linux Server?
- How Do I Verify Data Consistency Between the Source and Target Servers?
- Can I Use a Temporary AK/SK Pair for Migration?
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