DataDirect Networks EF4024 FC Setup Manual
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System Components96-30065-001 Rev. A0 DataDirect Networks EF4024 FC RAID System Setup Guide | 131.5 CompactFlashDuring a power loss or controller failure, data stored in cache is saved off to non-volatilememory (CompactFlash). The data is restored to cache, and then written to disk after theissue is corrected. To protect against writing incomplete data to disk, the image stored on theCompactFlash is verified before committing to disk.The CompactFlash card is located at the midplane-facing end of the controller module asshown in Figure 7. It is used for cache recovery only.CAUTION : The CompactFlash card should only be removed for transportablepurposes. To preserve the existing data stored in the CompactFlash, youmust transport the CompactFlash from the failed controller to thereplacement controller. Failure to do so will result in the loss of datastored in the cache module. The CompactFlash must stay with the sameenclosure. If the CompactFlash is used/installed in a different enclosure,data loss/data corruption will occur. Contact DDN Support for guidanceon replacement procedure.IMPORTANT: In dual-controller configurations featuring one healthy partnercontroller, there is no need to transport failed controller cache to areplacement controller because the cache is duplicated between thecontrollers (subject to volume write optimization setting).1.6 Supercapacitor PackTo protect controller module cache in case of power failure, each controller enclosuremodel is equipped with supercapacitor technology, in conjunction with CompactFlashmemory, built into each controller module to provide extended cache memory backup time.The supercapacitor pack provides power for backing up unwritten data in the write cacheto the CompactFlash, in the event of a power failure. Unwritten data in CompactFlashmemory is automatically committed to disk media when power is restored. In the event ofpower failure, while cache is maintained by the supercapacitor pack, the Cache Status LEDflashes at a rate of 1/10 second on and 9/10 second off.Figure 7. CompactFlash Card in Controller ModuleCompactFlash Card |
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