How to find the disk size for an Avamar BMR restore

We had a scenario where a BMR (Bare Metal Restore) system state restore was required.

A skeleton VM was created with drives matching the original server and booted from the Avamar BMR ISO. The restore was kicked off and after 90% the restore failed. Why?

Because the disk sizes did not match. The VM had several disks, some were stripped volumes some as spanned volumes. When the restore skeleton VM was created, the Admins just matched the volumes to the old VM. Avamar has no visiblity of how the disks are laid out within the OS.

Example of how the disks were laid out in VMware and inside the OS - 

So the question is how do you find the disk size if the VM is down and you need a BMR restore?

Avamar has a very nice Avtar command line utility. I could not find an official document from EMC but there is bits and pieces of information on the web.

avtar.exe --help will give you a wide range of options.

Steps to find the drive size for a BMR restore -

• On your Windows workstation, install the Avamar client software and do not register it with the Avamar console.
• The default installation path will be - C:\Program Files\avs\
• Run the following command 

C:\Program Files\avs\bin>avtar.exe -x --server=IP_of_Avamar_Server --id=Username --ap=
Password --path=/clients/servername_FQDN 

--labelnum=label_number_of_the_backup_to_be_restored --internal --target=.\tmp\ .system_info

--target=.\tmp will create a tmp directory under avs\bin and the output of the command will be under this directory.

• There will be numerous XML files under \tmp.
• The useful files are CriticalVolumesMapping.xml and partitiontables.xml

CriticalVolumesMapping.xml will give you the details of how the disks are laid out within the OS. 

Example - 
-<VolumeMappings Version="2.0">

<Volume DiskNumbers="0" SubwidIdx="1" DisplayName="c:\" UniqueID="\\?\Volume{6e1e483e-8e40-11e1-a235-806e6f6e6963}\"/>
<Volume DiskNumbers="8,9" SubwidIdx="2" DisplayName="i:\" UniqueID="\\?\Volume{106195a0-5f22-11e4-b3e6-005056bc0037}\"/>
<Volume DiskNumbers="3,5,6,4" SubwidIdx="3" DisplayName="e:\" UniqueID="\\?\Volume{69f9f6c7-8e4f-11e1-a46f-005056bc0037}\"/>
<Volume DiskNumbers="1" SubwidIdx="4" DisplayName="g:\" UniqueID="\\?\Volume{a2f72c19-d096-11e5-a54e-005056bc0037}\"/>
<Volume DiskNumbers="0" SubwidIdx="5" DisplayName="\\?\volume{6e1e483d-8e40-11e1-a235-806e6f6e6963}\" UniqueID="\\?\Volume{6e1e483d-8e40-11e1-a235-806e6f6e6963}\"/>
</VolumeMappings>

We can clearly see that -

Disks 3,4,5,6 make up Logical volume E:

Disks 8,9 make up Logical volume I:

partitiontables.xml will provide you with the disk sizes

Example - 

-<PhysicalDisk NumPartitions="4" DiskSize_bytes="274872407040" PartioningScheme="MBR" MBRSignature="1720029347" DiskType="Fixed" DiskNumber="8" DiskSize_Gbytes="255" SectorSize_bytes="512">

-<PartitionList>

<Partition Size_bytes="274876826112" Start_bytes="32256" partStyle="MBR" SerialNumber_dec="0" SerialNumber_hex="0" PartitionNumber="0" Size_Gbytes="255" Type="Alternate Linux swap" Bootable="false"/>

<Partition Size_bytes="0" Start_bytes="0" partStyle="MBR" SerialNumber_dec="0" SerialNumber_hex="0" PartitionNumber="1" Size_Gbytes="0" Type="Empty" Bootable="false"/>

<Partition Size_bytes="0" Start_bytes="0" partStyle="MBR" SerialNumber_dec="0" SerialNumber_hex="0" PartitionNumber="2" Size_Gbytes="0" Type="Empty" Bootable="false"/>

<Partition Size_bytes="0" Start_bytes="0" partStyle="MBR" SerialNumber_dec="0" SerialNumber_hex="0" PartitionNumber="3" Size_Gbytes="0" Type="Empty" Bootable="false"/>

</PartitionList>

</PhysicalDisk>

-<PhysicalDisk NumPartitions="4" DiskSize_bytes="274872407040" PartioningScheme="MBR" MBRSignature="1720029346" DiskType="Fixed" DiskNumber="9" DiskSize_Gbytes="255" SectorSize_bytes="512">

-<PartitionList>

<Partition Size_bytes="274876826112" Start_bytes="32256" partStyle="MBR" SerialNumber_dec="0" SerialNumber_hex="0" PartitionNumber="0" Size_Gbytes="255" Type="Alternate Linux swap" Bootable="false"/>

<Partition Size_bytes="0" Start_bytes="0" partStyle="MBR" SerialNumber_dec="0" SerialNumber_hex="0" PartitionNumber="1" Size_Gbytes="0" Type="Empty" Bootable="false"/>

<Partition Size_bytes="0" Start_bytes="0" partStyle="MBR" SerialNumber_dec="0" SerialNumber_hex="0" PartitionNumber="2" Size_Gbytes="0" Type="Empty" Bootable="false"/>

<Partition Size_bytes="0" Start_bytes="0" partStyle="MBR" SerialNumber_dec="0" SerialNumber_hex="0" PartitionNumber="3" Size_Gbytes="0" Type="Empty" Bootable="false"/>

In the above scenario, Disks 8 and 9 together make up Volume I: and from the partitiontables.xml file you know the total size of I: will be 510GB. While creating the skeleton VM you will create a 510 GB drive.

Once you create the exact size and number of drives required, Avamar will perform a restore without any hiccups. 

Problem solved !