m4_comment([$Id: cache.so,v 10.3 2002/09/26 01:38:32 bostic Exp $])m4_ref_title(Programmer Notes,    Disk drive caches,, program/ram, program/copy)m4_p([dnlMany disk drives contain onboard caches.  Some of these drives includebattery-backup or other functionality that guarantees that all cacheddata will be completely written if the power fails.  These drives canoffer substantial performance improvements over drives without cachingsupport.  However, some caching drives rely on capacitors or othermechanisms that guarantee only that the write of the current sectorwill complete.  These drives can endanger your database and potentiallycause corruption of your data.])m4_p([dnlTo avoid losing your data, make sure the caching on your disk drives isproperly configured so the drive will never report that data has been writtenunless the data is guaranteed to be written in the face of a power failure.Many times, this means that write-caching on the disk drive mustbe disabled.])m4_page_footer