Troubleshooting an App Node to App host migration

You can troubleshoot the following issues if you come across them with your App Node to App Host migration.

App Node backup file MD5 checksum is d41d8cd98f00b204e9800998ecf8427e

An MD5 checksum of d41d8cd98f00b204e9800998ecf8427e indicates that the App Node backup file is a zero-byte file. Insufficient disk space available for the backup file might be the cause. If you receive this value for the checksum:

Use ssh to log in to your App Node as the root user.
Type the following command and note the space available in /store.
```
df -h /store
```
Type the following command and note the used space in /store/backup/marathon.
```
du -hs /store/backup/marathon/
```
Type the following command and note the used space in /store/docker/volumes.
```
du -hs /store/docker/volumes/
```
Compare the total space that is used by /store/docker/volumes to the total space available in /store. You need at least 1 to 1.5 times as much free space in /store as space used by /store/docker/volumes. If you don't have enough free space in /store, check to see whether you have enough used space in /store/backup/marathon to make up the difference.
For example, if the space used by /store/docker/volumes is 100 GB, and the space available in /store is 90 GB, you don't have enough free space for the backup file. If /store/backup/marathon is using 10 GB or more of space, you can free space in /store/backup/marathon.
Back up and remove files from /store/backup/marathon to free up space by following these steps:
1. On your Console, create an App Node back up directory under /store by typing the following command.
```
mkdir /store/app_node_backup
```
2. Copy marathon backup files from the App Node to the Console by typing the following command.
```
scp root@<appnode_IP_address>:/store/backup/marathon/backup.marathon-volumes.qapp.*.tgz /store/app_node_backup/
```
3. Check the MD5 checksum of the marathon backup files on the Console by typing the following command.
```
ls /store/app_node_backup/backup.marathon-volumes.qapp.*.tgz | xargs md5sum
```
4. On the App Node, check the MD5 checksum of the marathon backup files by typing the following command.
```
ls /store/backup/marathon/backup.marathon-volumes.qapp.*.tgz | xargs md5sum
```
5. Verify that both checksum values are the same. If they are, remove the marathon backup files from the App Node by typing the following command on the App Node.
  Warning: The rm -rf command removes a directory and all files in it. Ensure that you enter the command exactly as shown here.
```
rm -rf /store/backup/marathon/*
```
Run the App Node data backup script by following step 3 in Migrating from an App Node to an App Host, and complete that procedure.