...storage

By stable storage, we mean a duplex-disk setup which is safe against single disk failures.

...page

The log consists of a set of pages. Reads and writes to the log are done in units of a page. The reason for this is that logs are typically maintained in a separate disk and this disk can be read/written only in units of a page, i.e., disk block.

...LSN

Throughout this report, the terms next LSN and last LSN are used interchangeably.

...need

Whenever a log record is written, a logrecord::LOG_END is appended to it. This allows detection of end of log as described in Section 5.4.6. Therefore, the length of the log record used in this computation is one more than the length of the supplied log record.

...occurred

We are assuming that the first five log records exactly fit a page. This need not be the case. If a log record is split across pages, we can treat it as though it were two log records, one fitting into the current page and the other fitting into a new page. The only difference is that the second part does not get an LSN.

...ID

Each writer will down(sp) before checking ID and up it just before writing or sleeping.