| 摘要 |
A log of transactions is maintained on a persistent storage device. When a block of storage is allocated or deallocated, this transaction is recorded. If the persistent storage device is allowed to be slightly obsolete (i.e., not fully up-to-date), the log stored on the persistent storage device does not necessarily have to be updated right away. By delaying log updating until a certain number of transactions have transpired, memory seeks can be reduced, significantly improving performance. Further, directory information on the persistent storage device may be periodically updated from the log. This is preferably done infrequently enough so that the amortized cost for updating directory information is low.
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