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FN-2018-421 - ERS Flash Failure due to Excessive Writes

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Information

 
Notice Summary
Prior to release ERS 4800 release 5.11.1, ERS 4900 / ERS 5900 release 7.5.0, these platforms may experience premature failure of non-volatile RAM (NVR) due to an issue with configuration auto-save frequency for non-base units. If this issue is encountered it will impact the ability to save switch configurations on the non-base units of a stack. A software fix to address this is available for the ERS 4800 (release 5.11.1 or later), ERS 4900 and ERS 5900 series platforms (release 7.5.0 or later). Deployments running the impacted software versions should upgrade as soon as possible to the latest releases for these platforms to avoid the failure. For ERS 4900 and 5900 switches that have encountered flash write failures, field recovery may be possible with release 7.6.1 and above.
Background
A feature interaction has been identified on certain versions of ERS 4800, ERS 4900 and ERS 5900 software which results in an excessive write frequency to the NVR Flash partitions storing the configuration data on non-base units in stacks of these platforms. This can potentially lead to early-life failure of the flash component which can be avoided through implementation of the remedial actions or software upgrades described in this notice.

The interaction requires all of the following conditions to be present in order for the issue to occur:
  1. Auto-save enabled (default)
  2. Last local active read/write user's inactivity period is reached
  3. Switch is a non-base unit in a stack
  4. Stack is running affected software releases
Impact
Flash components used on these switches are rated for a large, but finite, number of write cycles before component wear leads to failure. Once the flash component fails, the configuration data will not be saved to the switch. Please contact Extreme GTAC for assistance if NVRAM write failures are encountered.
Products Affected
  • Ethernet Routing Switch 4900 Series
  • Ethernet Routing Switch 5900 Series
  • Ethernet Routing Switch 4800 Series
Software Affected
  • ERS 4900/5900 7.2.x
  • ERS 4900/5900 7.3.x
  • ERS 4900/5900 7.4.x
  • ERS 4800 5.10.x
Symptoms
  • Switch logging NVRAM errors in log file
Type Unit Time                          Idx  Src Message
---- ---- ----------------------------- ---- --- -------
C    3    2018-05-15 23:22:08 GMT-04:00 43   NVR FSH - Error: Failed to erase flash address 848a0000 located in the Auxiliary Config
C    3    2018-05-15 23:23:19 GMT-04:00 44   NVR FSH - Error: Failed to erase flash address 840c0000 located in the Config-1
C    3    2018-05-15 23:28:25 GMT-04:00 50   NVR FSH - Error: Failed to erase flash address 84ca0000 located in the Audit Region
C    3    2018-05-15 23:28:49 GMT-04:00 51   NVR FSH - Error: Failed to erase flash address 84ce0000 located in the MCFG Block
C    3    2018-05-15 23:28:51 GMT-04:00 52   NVR FSH - Error: Failed to erase flash address 84d00000 located in the Backup MCFG Block
S    3    2018-05-15 23:29:18 GMT-04:00 57   NVR Audit commit failed (cannot write flash sector(s))
 
  • Cannot save configuration
ERS#save config
% Could not copy to nvram

ERS#copy config nvram
% Could not copy to nvram
 
  • Excessive flash writes recorded
ERS#show flash history unit 2
----------------------------------------------------------------------------
FLASH Write History Unit 2:
----------------------------------------------------------------------------
Section            Number of writes
----------------------------------------------------------------------------
Diagnostics Image:       2
Agent Image:           5
Config Area 1:           197021
Config Area 2:           0
Auxiliary Config Area:       197021
MCFG Block :           197025
Audit log Area :       1491
---------------------------------------------------------------------------
* Number of minimum guaranteed writes: 100 000
---------------------------------------------------------------------------
  • Only affects NBU switches in stack
  • Errors persist following reset of the stack
Workaround
The issue can be avoided by addressing either of the following options prior to flash failure:
  • Disable auto-save
  • Access switch periodically to ensure that at least one read/write user account remains active
  • Perform a software upgrade (see "solution" section below)
Once the flash write errors are encountered due to this issue, a recovery action is now possible with the ERS 4900/5900 7.6.1 release and will be included in a future release for the ERS 4800 series switches. Please contact Extreme GTAC for assistance.
 
Solution
A solution is available in ERS 4800 release 5.11.1 or later and ERS 4900 / ERS 5900 release 7.5.0 or later which addresses the excessive NVRAM write frequency. With ERS 4900 / ERS 5900 release 7.6.1, recovery for switches experiencing NVRAM write failures may be possible. Please contact Extreme GTAC for evaluation and assistance.

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