EMC PowerPath limitations

KB ID:
2771
Product:
Veeam Agent for Linux
Version:
2.x, 3.x
Published:
Last Modified:
2020-04-30

Challenge

If a Linux server has EMC PowerPath devices attached, all the underlying block devices representing the network paths to the server are included in the backup created by Veeam Agent for Linux 2.x. Therefore, an extra amount of data is stored inside the backup file.

In Veeam Agent for Linux 3.x such devices are skipped from processing completely, resulting in the "No objects to backup" error or PowerPath devices missing from the backup.

Cause

Currently, Veeam Agent for Linux detects only the DM-Multipath based devices as aggregated. Because of this, the following applies to the product:

  • In version 2.x, all the block devices with underlying EMC PowerPath aggregated devices are also included in the backup file if the ‘Entire machine’ backup mode is selected in the backup job settings.
  • In version 3.x, block devices with the same MBR ID cannot be backed up. Both individual paths and aggregated device are considered different block devices and are skipped from processing.
EMC PowerPath support will be introduced in future versions of Veeam Agent for Linux.

Solution

Veeam Agent for Linux 2.x


Configuring Veeam Agent Backup Job on Veeam Agent Machine

Configure Volume-level backup job in Veeam Agent for Linux and include only aggregated EMC PowerPath devices and regular block devices into the backup, do not include block devices representing the network paths of EMC PowerPath. In this case, no extra data will be stored inside the backup file, only the exact amount of real data. For example, in following output you may see EMC PowerPath aggregated device name and underlying devices:
[root@localhost ~]# powermt display dev=all
Pseudo name=emcpowerea
Symmetrix ID=000343607604
Logical device ID=07BA
Device WWN=60000980000262604497023030364553
state=alive; policy=SymmOpt; queued-IOs=0
==============================================================================
--------------- Host ---------------   - Stor -  -- I/O Path --   -- Stats ---
###  HW Path               I/O Paths    Interf.  Mode     State   Q-IOs Errors
==============================================================================
   6 lpfc                   sdef       FA 10f:00 active   alive      0      0
   5 lpfc                   sdcm       FA  6f:00 active   alive      0      0
   4 lpfc                   sdau       FA  7f:00 active   alive      0      0
   3 lpfc                   sdb        FA 11f:00 active   alive      0      0
In this example there are following devices:
 
/dev/emcpowerea – aggregated EMC PowerPath device
/dev/sdef, /dev/sdcm, /dev/sdau, /dev/sdb – underlying block devices representing the network paths
 
Accordingly, to mount table /dev/emcpowerea partitioned and mounted under /data folder:
root@localhost:~# mount | grep emcpowerea
/dev/emcpowereap1 on /data type ext4 (rw,relatime,errors=remount-ro,stripe=256,data=ordered)
In this case block device /dev/emcpowereap1 must be included into backup as shown on image below
User-added image
sdef, sdcm, sdau and sdb should be left unchecked.
 
Configuring Veeam Agent Backup Job in Veeam Backup & Replication
If Veeam Agent backup job is managed by the backup server, you may configure the same via Veeam B&R console. For example, choose type ‘Volume level backup’ for your backup job:
User-added image

And enter the block device names or mountpoint paths as shown below:

User-added image
User-added image

Veeam Agent for Linux 3.x

You must exclude all individual IO paths in the /etc/veeam/veeam.ini configuration file using the ignoreDevices parameter under the [backup] section. This parameter is hidden in the default veeam.ini file, and you must add it manually.

The following example displays the list of individual IO paths for the /dev/emcpowerea block device (from the example above, retrieved via the powermt output): 

/dev/sdef;/dev/sdcm;/dev/sdau;/dev/sdb

Specify these paths in the ignoreDevices parameter in the veeam.ini file using a semicolon without a whitespace as a separator. For example:

[backup]
# Backup cluster alignment logarithm
# clusteralign= 3

# Ignore inactive LVM logical volumes during backup
# ignoreinactivelvm= false

# IO rate limit, from 0.01 to 1.0
# ioratelimit= 0.9

# CPU priority for veeamagents, from 0 to 19
# priority= 10

# Verbose logging of device enumeration
# verbosedevenumlogging= false

ignoreDevices= /dev/sdef;/dev/sdcm;/dev/sdau;/dev/sdb

Save the veeam.ini file and make sure no backup or restore sessions are running on the Veeam Agent machine. If no backup or restore sessions are running, restart the veeamservice daemon so that the new values are picked up from the configuration file.

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