Data Domain Virtual Tape Library: VTL device are not automatically discovered after upgrade, reboot or FS restart
Summary: After an upgrade, reboot or FS restart, some server can't see VTL device. Only with DDOS higer than 5.2 and lower than 6.0
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This article is not tied to any specific product.
Not all product versions are identified in this article.
Symptoms
The initiator side not seeing the same SCSI devices mapping to the DD SCSI targets after the DD has rebooted for some reason.
This requires the initiator to re-scan the SCSI bus to find out the new devices, and the backup application to see the targets again.
Backup media server doesn't automatically detect VTL devices after Data Center power cycle.
This issue may relate to the sequence in which the various devices are powered up: media server, SAN switches, Data Domain, etc.
An additional reason for the backup failure if you power up media server first, then other storage devices.
Some server or NAS connected to the VTL can't see tape drive after upgrade, reboot or FS restart.
But when troubleshooting the issue you don't found any issue and you have following :
This requires the initiator to re-scan the SCSI bus to find out the new devices, and the backup application to see the targets again.
Backup media server doesn't automatically detect VTL devices after Data Center power cycle.
This issue may relate to the sequence in which the various devices are powered up: media server, SAN switches, Data Domain, etc.
An additional reason for the backup failure if you power up media server first, then other storage devices.
Some server or NAS connected to the VTL can't see tape drive after upgrade, reboot or FS restart.
But when troubleshooting the issue you don't found any issue and you have following :
- The initiator is properly zoned and listed "online" in the DataDomain.
- The access group is properly configured.
- If it's an upgrade, WWPN is the same than before.
- VTL service is up
- This issue is not seen before DDOS 5.3
- Some other server doesn't have this issue
- Reboot of this server can solve the issue
- Reboot of DD doesn't solve the issue
Cause
Since DDOOS 5.3 the VTL component is splited in 2 sub process: VTL & scsitarget.
Basically scsitarget enables FC port before completing protocol configuration, causing the initiator to send plogi/prli and start LUN discovery as soon as the target port link is up, but target hasn t completed its device and Access Group configuration yet at that point, resulting in not finding any physical LUN.
Resolution
The workaround of this issue is to reset the port or restart the scsi target daemon (keep VTL service up):
Reset the port:
Check the device list in the host.
Reset the port:
# scsitarget endpoint disable <the endpoint>
# scsitarget endpoint enable <the endpoint>
# scsitarget endpoint enable <the endpoint>
Check the device list in the host.
If you have multiple host impacted do this:
# scsitarget disable
# scsitarget enable
The customer needs to perform this workaround until the DDOS 6.0.
Additional Information
During Data Center power cycle, one should power up storage devices and SAN devices first, then power on the media server.
Affected Products
Data Domain Virtual Tape LibraryProducts
Data Domain Virtual Tape Library, Data Domain Virtual Tape Library for IBM I/OSArticle Properties
Article Number: 000059666
Article Type: Solution
Last Modified: 25 Sep 2024
Version: 3
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