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Delphix

System May Panic Due to Filesystem Free List Error (TB012)

Impact

The filesystem for the Delphix Engine maintains a free list of space that can be used for future allocations. In some cases, this free list can become inconsistent.  Subsequently when the free list is loaded, the system detects the inconsistency and forces a system panic and reboot.   In rare circumstances the inconsistent free list can be flushed to disk, and this can result in a panic loop in which the system would repeatedly panic during boot. 

Contributing Factors

This issue can affect appliances that have at any time run Delphix Engine 2.7.0, Delphix Engine 2.7.1, or Delphix Engine 2.7.1.1

Appliances that are actively running one of these affected releases may encounter the transient form of this error or, far more rarely, the persistent form.

Affected appliances that have already been upgraded to Delphix Engine 2.7.1.2 or later may only be impacted by the rare, persistent incarnation of this error. 

Symptoms

If the problem results in a single panic, virtual databases (VDBs) may experience a temporary suspension of service. In the system log of affected target hosts, messages like:

NFS server <ip address>  not responding

may be seen, where <ip address> is the network address of the affected Delphix server. 

If the rare, but persistent form of the issue occurs in which the appliance is caught in a panic loop, the Delphix Engine will be unavailable, and VDBs on the affected appliance will hang or abort. 

Relief/Workaround

Susceptible systems can include systems that are either running, or were previously running the affected releases. Customers with susceptible systems should contact Delphix Support to upgrade any susceptible appliances. At the time of upgrade, Delphix can determine if any free list inconsistency remains and repair it, as necessary. 

Resolution

A final resolution is available in Delphix Server 2.7.5.0.

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