Footnotes
- ...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.
ajitk@cs.wisc.edu, cjin@cs.wisc.edu