Why Is the File System Size Inconsistent Before and After the Migration?
Symptom
- After the migration, the used partition space on the target server is different from that on the source server.
- After the migration, a particular file size on the target server is different from that on the source server.
Possible Causes
If there are sparse files on the source server, the total size of the migrated files on the target server may be smaller than that on the source server. This is because rsync automatically truncates sparse files during transmission. The file system transparently converts metadata representing empty blocks into "real" blocks filled with null bytes at runtime.
You can check whether the files are consistent before and after the migration. For details, see Procedure.
In a UNIX file system, when the file displacement is greater than the file length, the next write operation will extend the file length and form a hole in the file, creating a sparse file. This is achieved by writing brief information (metadata) representing the empty blocks to disks instead of the actual "empty" space which makes up the block, thus consuming less disk space. The full block size is written to disk as the actual size only when the block contains "real" (non-empty) data.
Procedure
- Check the size of the file on the source server and the used disk space. The /tmp/test-data.img file is used as an example.
- Check the size of the /tmp/test-data.img file.
ll /tmp/test-data.img
- Check the disk space occupied by /tmp/test-data.img.
du -sh /tmp/test-data.imgFigure 1 Checking the file size
- Check the size of the /tmp/test-data.img file.
- After the migration is complete, check the size of the migrated file on the target server. Figure 2 shows that the used disk space decreases after the migration.
- Run the following command on the source server and target server to obtain the sha256 values of the files to determine whether the files are the same.
If the sha256 values of the files are the same, the file content is consistent.
sha256sum /tmp/test-data.img
Figure 3 Obtaining the sha256 value
Target Server Configuration and Launch FAQs
- What Are the Differences Between Target and Source Servers After the Migration?
- How Will the Authentication of a Target Server Change?
- How Do I Optimize a Windows Target Server After the Migration Is Complete?
- How Do I Fix the Error "SMS.1113 Failed to reconfigure partition details on the target server" When I Launch the Target Server?
- After a Windows Server Was Migrated, Why Is the Used Space of C: Drive Increased?
- How Do I Uninstall the SMS-Agent from the Source and Target Servers After the Migration Is Complete?
- How Do I Configure the Yum Repository for the Target Server After the Migration Is Complete?
- Why Is the File System Size Inconsistent Before and After the Migration?
- Why Can't I See Data Disks on a Windows Target Server After Migration?
- Why Can't a Windows Target Server Access the Internet After the Migration?
- Why Is the System Recovery Options Window Displayed When the Target Server Is Started?
- How Do I Fix a GRUB Error Because an XFS Volume Is Mounted to the /boot Partition?
- What Do I Do If a Target Server Fails to Be Created?
- How Do I Troubleshoot a MySQL Startup Failure on the Target Server After the Migration?
- How Do I Resolve Error "SELinux targeted" When I Start a Linux Target Server After the Migration Is Complete?
- Why Do the Agent Plug-ins from the Source Cloud Service Provider Exist on the Target Server After the Migration Is Complete?
- Why Is the Usable Memory (RAM) Less Than the Total Installed Memory on a Target Server Running 64-bit Windows?
- After the Migration Is Complete, Will Deleting the Target Server Configuration or Server Record Affect the Source or Target Server?
- How Do I Fix BSOD Errors When I Start a Windows Target Server After the Migration?
- How Do I Fix Startup Failures of a Windows Target Server After the Migration?
- If I Change the Password of the Source Server and Perform an Incremental Replication After the Full Migration Is Complete, Will the New Password Be Synchronized to the Target Server?
- What ECS Types Are Supported by SMS?
Feedback
Was this page helpful?
Provide feedbackThank you very much for your feedback. We will continue working to improve the documentation.See the reply and handling status in My Cloud VOC.
For any further questions, feel free to contact us through the chatbot.
Chatbotmore