vCenter VAMI file-based backup fails for VCSA 8.0 Update 3 when using a short name as backup target

Products

• VMware vCenter Server

Issue/Introduction

After upgrading from vCenter version 7.0 Update 3 to 8.0 Update 3 or later versions, file-based backups via VAMI UI fail to complete successfully. The following error is reported:

A General System Error is reported by backup server

When reviewing /var/log/vmware/applmgmt/applmgmt.log, the following error can be seen:

<timestamp> [87321]ERROR:plugins.FtpStorageIOLib:ftps cmd failed. RC: 6, Err: curl: (6) Could not resolve host: <shortname of backup server>
, Cmd: ['/usr/bin/curl', '--fail', '-u', 'svc-app-ftpvcsa:****', '--connect-timeout', '120', '--ssl-reqd', '-k', '--noproxy', '*', '--silent', '--show-error', '--list-only', 'ftp://<shortname of backup server>/<shortname of vCSA>']

 

Environment

VMware vCenter Server 8.0.3

Cause

The resolv.conf  (/etc/resolv.conf) file contains the line:

search .

 

The backup failure is caused by the use of a short hostname (SN) instead of the Fully Qualified Domain Name (FQDN) when configuring the backup destination. Short names can cause DNS resolution issues, particularly in environments with multiple network segments or complex DNS configurations.

Having "search ." in resolv.conf file means that search domain(s) have not been configured.

Resolution

Use the Fully Qualified Domain Name (FQDN) of the backup target, when specifying the backup destination. This is the recommended best practice, as it ensures consistent DNS resolution and avoids issues across various network setups.

Alternatively you can configure search domain(s):

1. Open an SSH session to vCSA and enter BASH:

   shell

2. Issue the following command to launch network configuration:

   /opt/vmware/share/vami/vami_config_net

3. Select option 4 to access the DNS configuration:

   # /opt/vmware/share/vami/vami_config_net
   
    Main Menu
   
   0)      Show Current Configuration (scroll with Shift-PgUp/PgDown)
   1)      Exit this program
   2)      Default Gateway
   3)      Hostname
   4)      DNS                                                      <===============
   5)      Proxy Server
   6)      IP Address Allocation for eth0
   Enter a menu number [0]:
   

4. Follow the wizard and add your search domain as "Search Path":

   DNS Server 1 [###.###.#.##]:
   DNS Server 2 (optional) [###.###.#.#]:
   Domain Name (optional) []: example.domain
   Search Path (space separated) (optional): example.domain example.domain.1    <===

5. Save the configuration, then exit the tools with "1"
6. After making the change, the /etc/resolv.conf file should be updated with the same change:

   search example.domain example.domain.1

 

Additional Information

Order of precedence for name resolution is:

/etc/hosts

#.#.#.# shortnameofsystem fqdnofsystem

Where system is the name of the system you want to statically resolve if not using DNS. This entry must be manually maintained.

and then by DNS search domain suffix,

/etc/resolv.conf

search Search list for host-name lookup.

              By default, the search list contains one entry, the local
              domain name.  It is determined from the local hostname
              returned by gethostname(2); the local domain name is taken
              to be everything after the first '.'.  Finally, if the
              hostname does not contain a '.', the root domain is assumed
              as the local domain name.

Note: If there are multiple search directives, only the search list from the last instance is used.