Dell PowerVault MD3260i - Manual (Page 51)

The RAID controller module fails over if it experiences up to 10 single-bit errors, or up to three multi-bit errors.
PCI Errors
The storage array firmware can detect and only recover from PCI errors when the RAID controller modules are
configured for redundancy. If a virtual disk uses cache mirroring, it fails over to its peer RAID controller module, which
initiates a flush of the dirty cache.
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