Dell Unity: When data reduction is enabled on some versions, high load conditions can cause an SP to panic (User Correctable)
Summary: In code versions 4.5.0 to 5.0.2, a code deficiency exists which, under certain high load conditions and where data reduction is enabled, can cause a Storage Processor to panic.
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Symptoms
In code versions 4.5.0 to 5.0.2, a code deficiency exists which, under certain high load conditions, can cause a Storage Processor (SP) to panic. Unity must have data reduction enabled in order to experience this panic.
Cause
The issue is due to a change in 4.5.0 and later code. The Persistent File Data Cache (PFDC) is no longer bypassed on arrays with data reduction enabled during heavy I/O periods. Under certain heavy IO conditions, if the datalog fills up and writes start accumulating in a pending list, the possibility exists that a race condition may occur which could corrupt the pending list. If this occurs, an SP panic could result.
In most known instances these have been single SP panics and have not caused any data unavailable. In a small number of cases, both SPs have panicked, which can cause data unavailable.
In most known instances these have been single SP panics and have not caused any data unavailable. In a small number of cases, both SPs have panicked, which can cause data unavailable.
Resolution
This issue is fixed in Dell Unity Operating Environment (OE) version 5.0.3. Upgrade to this version in order to obtain this fix.
Instructions for upgrading can be found here:
Dell EMC Unity: How to Upgrade Dell EMC Unity OE code, (User Correctable).
Affected Products
Dell EMC Unity FamilyProducts
Dell EMC Unity Family |Dell EMC Unity All Flash, Dell EMC Unity Family, Dell EMC Unity HybridArticle Properties
Article Number: 000070373
Article Type: Solution
Last Modified: 16 Apr 2025
Version: 3
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