Boot Page

  • Sugesh Kumar

    One Orange Chip

    Points: 27311

    Comments posted to this topic are about the item Boot Page

    Cheers,
    Sugeshkumar Rajendran
    SQL Server MVP
    http://sugeshkr.blogspot.com

  • Christian Buettner-167247

    SSChampion

    Points: 13729

    I think the answer is incomplete, the log file also contains the boot page:

    One of the system pages stored in both the primary data file and the first log file is a database boot page that contains information about the attributes of the database.

    ms-help://MS.SQLCC.v9/MS.SQLSVR.v9.en/udb9/html/39e00ebe-c9b7-4d53-90bd-15de2015fd34.htm

    Best Regards,

    Chris Büttner

  • dunnjoe

    SSCrazy

    Points: 2180

    Christian,

    I found this very informative web-page that states it is always page 9 in file 1. It goes on to give excellent details on what is on the page.

    Joe

    http://www.sqlskills.com/blogs/paul/2008/07/11/SearchEngineQA20BootPagesAndBootPageCorruption.aspx

  • StarNamer

    SSCrazy Eights

    Points: 8633

    After looking at the reference in the asnwer (the ms-help: ref doesn't work for me) I tried the 'DBCC DBINFO()' statement and just got a message 'DBCC execution completed. If DBCC printed error messages, contact your system administrator.'!

    More searching revealed that the command 'dbcc traceon(3604)' was needed as well! Perhaps this should have been mentioned somewhere!

    Also a document search for either 'bootpage' or 'boot page' came up with nothing in the 2005 BOL and nothing that I could see that was relevant in MSDN (though I didn't check every MSDN link, just skimmed the intros).

    Derek

  • Miles Neale

    SSChampion

    Points: 13147

    If you are looking for more information on this you might read at

    http://www.sqlskills.com/blogs/paul/2008/07/11/SearchEngineQA20BootPagesAndBootPageCorruption.aspx

    Miles...

    Not all gray hairs are Dinosaurs!

  • Scott Klein-508332

    Say Hey Kid

    Points: 692

    I agree. I spent 1/2 hour googling this. I found BOL stuff, stuff on MSDN, but nothing like the information provided in the answer link.

  • Mark D Powell

    SSCarpal Tunnel

    Points: 4453

    But Booksonline also contains this quote "Log files do not contain pages; they contain a series of log records."

    Blame MS not the author or question as I found the same section you did but I also found this

    >>

    Only database pages can be restored. Page restore cannot be used to restore the following:

    Transaction log

    Allocation pages—Global Allocation Map (GAM) pages, Shared Global Allocation Map (SGAM) pages, and Page Free Space (PFS) pages. For more information, see Managing Extent Allocations and Free Space.

    Page 0 of all data files (the file boot page)

    Page 1:9 (the database boot page)

    Full-text catalog

    <<

    MS documentation leaves a lot to be desired.

    -- Mark D Powell --

  • Scott Klein-508332

    Say Hey Kid

    Points: 692

    True, BOL could be better, but I certainly won't blame anyone but myself for not finding the correct answer. I was probably Googling the wrong term, who knows. Whether I got the question right or wrong, I learned something new today.

  • Scott Klein-508332

    Say Hey Kid

    Points: 692

    Actually, I found out what my search error was. I was Googling "bootpage", and not "boot page". If you Google the later, the answer is the first link displayed.

  • Christian Buettner-167247

    SSChampion

    Points: 13729

    Christian Buettner (8/21/2008)


    I think the answer is incomplete, the log file also contains the boot page:

    One of the system pages stored in both the primary data file and the first log file is a database boot page that contains information about the attributes of the database.

    ms-help://MS.SQLCC.v9/MS.SQLSVR.v9.en/udb9/html/39e00ebe-c9b7-4d53-90bd-15de2015fd34.htm

    Here is the MSDN link for those where the BOL link did not work:

    http://msdn.microsoft.com/en-us/library/ms179316(SQL.90).aspx

    Best Regards,

    Chris Büttner

  • Christian Buettner-167247

    SSChampion

    Points: 13729

    Mark D Powell (8/21/2008)


    But Booksonline also contains this quote "Log files do not contain pages; they contain a series of log records."

    Blame MS not the author or question as I found the same section you did but I also found this

    Hi Mark, I am not blaming the author, just wanted to note that the log also stores the boot page.

    Just for additional confusion, check this info from BOL:

    The format of log records and pages is not constrained to follow the format of data pages.

    http://msdn.microsoft.com/en-us/library/ms190925(SQL.90).aspx

    I "think" that the info from your quote is incorrect (but of course correctly quoted from BOL).

    It might be possible that the log contains both, pages for the header information, and log records for the log data. Or maybe the log reords are actually stored in pages as well.

    But MS only knows 😉

    Best Regards,

    Chris Büttner

  • Anipaul

    SSC-Insane

    Points: 24681

    Thanks guys, I learnt something new from your links...

  • Mark D Powell

    SSCarpal Tunnel

    Points: 4453

    I think the problem is the first quote should really say "data pages". I do not think the internal format of the log uses "pages" but rather places the data, copy of pages, into log records. The line you reference about not having to use the data page format hints that the original format is not maintained hence the logs do not contain pages. Yet, you can find the term used in the manuals.

    The real problem is terminology. Page and block are often used as synonyms Really, a page should refer to the size of the IO used in OS page sets and the term should not be used to describe the database logical structure size or IO block size. But the technical writers have a bad habit of intermixing terms and leaving out qualifying adjectives that would be very beneficial to us mere users of the software.

    The Oracle manuals are not much different though the database itself does offer a log more visibility into its internal structures

    We live and learn (hopefully).

    -- Mark D Powell --

  • TomThomson

    SSC Guru

    Points: 104773

    The somewhat contradictory MS documentation is a bit of a mess. Anyway, it seems clear that if you lose File 1 page 9 in a mirrored database you can't even recover that page from the mirror http://msdn.microsoft.com/en-us/library/bb677167.aspx using the built-in recovery mechanism included in mirroring, no can you recover it by any other shortcut means - your database is dead until full recovery is done by one means or another (effectively blowing the whoe database away and recovering it from backups or with snapshot replication from a working copy or some equivalent equivalent mechanism) - at least I'm not aware of any means of recovering that page from the log file, so even though it appears that there is a copy in the log file it doesn't seem to be very useful (I suppose you might be able to do something with a physical level disc editor, but that's way outside the scope of SQL).

    Tom

  • scottm30

    Ten Centuries

    Points: 1094

    Great question considering 64% of the answers were incorrect! I came across this issue a short while ago which jogged my memory for this question, but nice to know. Thanks

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