During a power loss or controller failure, data stored in cache is saved off to non-volatile memory
(CompactFlash). The data is restored to cache, and then written to disk after the issue is corrected. To
protect against writing incomplete data to disk, the image stored on the CompactFlash is verified before
committing to disk.
The CompactFlash memory card is located at the midplane-facing end of the controller module as shown
below. Do not remove the card; it is used for cache recovery only.
Controller module pictorial
(Midplane-facing rear view)
For additional information, contact support.lenovo.com, select Product Support, and navigate to Storage
NOTE: In dual-controller configurations featuring one healthy partner controller, cache is duplicated
between the controllers (subject to volume write optimization setting).
To protect controller module cache in case of power failure, each controller enclosure model is equipped
with supercapacitor technology, in conjunction with CompactFlash memory, built into each controller
module to provide extended cache memory backup time. The supercapacitor pack provides energy for
backing up unwritten data in the write cache to the CompactFlash, in the event of a power failure.
Unwritten data in CompactFlash memory is automatically committed to disk media when power is restored.
In the event of power failure, while cache is maintained by the supercapacitor pack, the Cache Status LED
flashes at a rate of 1/10 second on and 9/10 second off.
CompactFlash memory card
Figure 1 1 CompactFlash memory card