понедельник, 7 апреля 2008 г.

RAID- policy

Здесь Policy нужно перевести как "правила", что подразумевает не четкие критерии, а возможность установки того или иного параметра (в зависимости от целей и возможностей).

Выбор настроек кэширования (Cache Options and Settings)-

Cache options and settings can be unique for each logical drive.

Cache Write Policy

Write Through - I/O completion is signaled only after the data is written to the hard disk.
Write Back - I/O completion is signaled when data is transferred to cache. При использовании Write Back, для защиты данных находящихся в кэше в момент выключения питания, используется BBU - Battary Backup Unit.

Cache Policy

Direct I/O - When possible, no cache is involved for both reads and writes. The data transfers will be directly from host to disk and from disk to host.
Cached I/O - All reads will first look at cache. If a cache hit occurs, the data will be read from cache; if not, the data will be read from disk and the read data buffered into cache. All writes to drive are also written to cache.

Read Policy

No Read Ahead (Normal?) - Provides no read ahead for the logical drive having this option turned on.
Read Ahead - Additional consecutive stripes/lines are read and buffered into cache.
Adaptive (Adaptive Read Ahead?) - The read-ahead will be automatically turned on and off depending upon whether the disk is accessed for sequential reads or random reads

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