Log archive and change accumulation:
When the log is archived, it can be compressed therefore that it is convenient for media recovery. For disk objects log records are able to be sorted by cylinder then track then sector then time. Most likely all the records in the archived log belong to completed transactions. Therefore one only needs to keep redo records of committed (not aborted) transactions. Further merely the most recent redo record (new value) need be recorded. This compressed redo log is called as a change accumulation log. Because it is sorted by physical address media recover becomes a merge of the image dump of the object and its change accumulation tape.
FAST_MEDIA_RECOVERY: PROCEDURE (IMAGE, CHANGE_ACCUMULATION_LOG);DO WHILE ( ! END_OF_FILE IMAGE);READ IMAGE PAGE;UPDATE WITH REDO RECORDS FROM CHANGE_ACCUMULATION_LOG;WRITE IMAGE PAGE TO DISK;ENDEND;
This is a entirely sequential process (sequential on input files as well as sequential on disk being recovered) and thus is limited only by the transfer rates of the devices.
The construction of the change accumulation file is able to be done off-line as an idle task.
If media errors are rare as well as availability of the data isn’t a critical problem then one may run the change accumulation utilities when needed. This may set aside building change accumulation files that are never used.
Latest technology based Operating System Online Tutoring Assistance
Tutors, at the www.tutorsglobe.com, take pledge to provide full satisfaction and assurance in Operating System help via online tutoring. Students are getting 100% satisfaction by online tutors across the globe. Here you can get homework help for Operating System, project ideas and tutorials. We provide email based Operating System help. You can join us to ask queries 24x7 with live, experienced and qualified online tutors specialized in Operating System. Through Online Tutoring, you would be able to complete your homework or assignments at your home. Tutors at the TutorsGlobe are committed to provide the best quality online tutoring assistance for Operating System Homework help and assignment help services. They use their experience, as they have solved thousands of the Operating System assignments, which may help you to solve your complex issues of Operating System. TutorsGlobe assure for the best quality compliance to your homework. Compromise with quality is not in our dictionary. If we feel that we are not able to provide the homework help as per the deadline or given instruction by the student, we refund the money of the student without any delay.
Start Excelling in your courses, Ask an Expert and get answers for your homework and assignments!!