Notes and Constraints

Server specifications

• Windows: Source and target servers must have more than 1 CPU and 1 GB of memory each.
• Linux: Source and target servers must have at least 1 CPU and 1 GB of memory each.

CPU and memory

• The CPU usage of a source server must not exceed 80%.
• The available memory of a source server must be greater than 256 MB.

OSs

• Supported Windows OSs
• Supported Linux OSs
• A server running multiple OSs cannot be migrated.

Available disk space

• Windows: Partitions of 600 MB or larger require at least 320 MB free. Partitions smaller than 600 MB require at least 40 MB free.
• Linux: at least 200 MB of available space on the root partition

Disk quantity

SMS imposes a disk limit on source servers due to ECS constraints. While an ECS supports up to 24 disks, SMS reserves one slot for a temporary disk during migration. This means that a source server can have a maximum of 23 disks.

Disk size

• The mkfs tool included in the SMS agent image for Linux cannot create file systems larger than 16 TB. As a result, disks exceeding 16 TB are not supported on target servers. To ensure compatibility, you can adjust disk and partition settings of source servers to meet this requirement. This restriction does not apply to Windows servers.
• To migrate a source server with GPT disks, the paired disks on the target server must at least be 1 GB larger.

File systems

• Windows:
  • Boot partitions: FAT32 and NTFS file systems are supported.
  • Non-boot partitions: Only NTFS file systems are supported.
• Linux: Only Ext2, Ext3, Ext4, VFAT, and XFS file systems are supported.

Shared file systems

Only files on local disks can be migrated. Shared file systems cannot be migrated.

For example, files in Network File System (NFS), Common Internet File System (CIFS), and Network Attached Storage (NAS).

Nested LVM systems

Nested LVM systems cannot be migrated.

Required components

Source servers must contain the components required for migration.

• Windows: WMI and VSS
• Linux: SSH (such as OpenSSH), rsync, and GRUB

Source character set encoding

Windows: Code page 437 and code page 936 are supported.

Linux: UTF-8 is supported.

Linux source SSH key algorithm

Supported key algorithms include ssh-rsa, rsa-sha2-256, and rsa-sha2-512.

Source server quantity

A maximum of 1,000 source servers are allowed per account. Delete the records of migrated servers in a timely manner so that other servers can continue to be migrated.

Number of concurrent migrations

A maximum of 200 source servers can be migrated at the same time.

External storage of servers

SMS cannot migrate data from the external storage attached to a source server.

Encrypted files

SMS cannot migrate OSs that contain protected folders or encrypted volumes.

Encrypted systems

SMS cannot migrate OSs that are encrypted, such as Windows OSs protected with BitLocker.

Servers that run multi-node databases and Active Directory Domain Services (AD DS)

SMS cannot migrate servers that host active directories or multi-node databases.

Data of database applications and domain controller applications

SMS cannot migrate data of database applications and domain controller applications.

Applications bound to hardware

SMS cannot migrate OSs that contain applications bound to hardware.

Dynamic disks

Dynamic disks in Windows systems are migrated as basic disks. After the migration is complete, the target server will not have dynamic disks.

Unmounted or uninitialized disks (empty disks)

SMS only migrates data on disks that are mounted and actively used on a source server. Data on unmounted or uninitialized disks will not be migrated.

SMS requires that the source and target servers have the same number of disks, including any unmounted or uninitialized disks.

• If you use an existing server as the target, make sure it has the same number of disks as the source server, including unmounted or uninitialized ones. After the migration is complete, you can delete any unmounted or uninitialized disks from the target server if they are no longer needed.
• If you allow the system to create a new target server, the system will automatically create a server with the same number of disks as the source server, including unmounted or uninitialized disks. After the migration is complete, you can delete any unmounted or uninitialized disks from the target server if they are no longer needed.

Servers with system volumes located on disks other than the first disk

SMS cannot migrate servers whose system volumes are not on the first disk.

Thinly-provisioned logical volumes

SMS cannot migrate thinly-provisioned volumes tagged with pool.

Servers with RAID arrays

SMS cannot migrate servers with RAID arrays.

Big data clusters and container clusters

SMS cannot migrate clusters including but not limited to container clusters and big data clusters.

Compressed RAM-based block devices (ZRAM devices)

SMS cannot migrate ZRAM devices. These devices are ignored during the collection phase, as they temporarily store compressed memory blocks. Manual configuration is required after the migration is complete.

Disk adjustment on Windows source servers

Incremental data on the source server is not synchronized. After you start the migration Agent on a source server, any disk adjustment, such as adding a disk or partition or scaling a partition, on the source server will prevent the migration task from synchronizing incremental data from the source server. To synchronize incremental data on the disk, perform the following steps:

1. Restart the source server.
2. Uninstall the migration Agent.
3. Reinstall the migration Agent.
4. Run the migration process again.