"EOF on read" error from a client

Resolution for "EOF on read" error from a client

This article is for Amanda Enterprise (AE).

Problem

• When starting a backup or performing a Host Check, the client reports an "EOF on read" error. The client can be pinged and has Amanda port 10080 open (or SSH port 22 open if using the SSH authentication method) yet any time a backup or Host Check is run, "EOF on read" is seen. 

Error

• In the NOTES section of a backup report from an email or on the Report| Backup page, a planner failure is reported:
  
  ERROR: planner Request to client.zmanda.com failed: EOF on read from client.zmanda.com
• In a Host Check on the Backup| What page or amcheck output, the following error is reported:
  
  WARNING: client.zmanda.com: selfcheck request failed: EOF on read from client.zmanda.com 

Cause

During the planning stage of a backup, amanda sends a SELFCHECK and SENDSIZE request to the client. The packet is received and acknowledged, but the Amanda Enterprise server never receives a response ACK and reports the EOF on read error. On the client, the logs indicate that client sent the SELFCHECK or SENDSIZE reply back to the server. There are three causes of this error:

• Possible cause 1: During the Host Check, Amanda client checks the hostname and performs a reverse lookup of the IP address. If the hostname request or
  reverse lookup fails, Amanda will be unable to authenticate the server and hence fails.
• Possible cause 2: During the backup, Amanda returns an estimate of the backup size in a SENDSIZE packet. This packet is typically larger than the standard
  MTU of 1500 bytes. If JumboFrames are enabled on the server or client, but not on all the network hardware, the packet will not be received by the server and
  dropped by the network.
• Possible cause 3: When using SSH public key authentication method instead of the standard "bsdtcp" authentication method with a UNIX or Linux client, the
  SSH authentication is failing during a Host Check and backup.
• Possible cause 4: Your SELinux policy on the client is preventing Amanda from reading the filesystem.

Solutions

• Solution to cause 1: For the Host Check error, verify if you can perform a forward and reverse lookup of the Amanda Enterprise server on the client. Check that the DNS
  name resolves to the correct IP address and that the IP address resolves to the correct hostname. Add entries into the /etc/hosts files if needed to correct any
  discrepancies.
• Solution to cause 2: For the backup/planner error, disable JumboFrames on the client and server or verify with the Network Architecture team that all network elements
  have JumboFrames enabled. Use Wireshark or tcpdump to verify that the packet is not being fragmented and dropped.
• Solution to cause 3: This failure is seen when using the SSH public key authentication method, please see "EOF on read" when using SSH authentication method.
• Solution to cause 4: Modify your SELinux policy as per the SELinux and Amanda Enterprise knowledge base article.