This integer reports the amount of memory, in kilobytes, allocated for the write cache, noting that because data is mirrored the actual usable amount is half the value shown. An admin uses this to understand true write-cache capacity available to buffer writes before committing them to disk. For example, cpqDaAccelMemory reporting 512 KB means only 256 KB is actually usable for buffering write data once the mirrored copy is accounted for.