Professional Web Applications Themes

DB2 incremental vs full back up - IBM DB2

"Siva" <mail2sivaj> wrote in message news:8a8e81a1.0307150952.610415b4posting.google.c om... > What is real advantage of incremental back up ? > > I was under the impression, that 'TRACKMOD' will track all the changes > made to the database since last full time backup, and it will backup > only those pages when do the incremental back up, and i was under the > impression when you issue 'incremental backup' db2 can figure pages > were changed in no time and backup those changes pretty fast. > > But in our, we have huge database, we want to implement the > incremental testing ...

  1. #1

    Default Re: DB2 incremental vs full back up


    "Siva" <mail2sivaj> wrote in message
    news:8a8e81a1.0307150952.610415b4posting.google.c om...
    > What is real advantage of incremental back up ?
    >
    > I was under the impression, that 'TRACKMOD' will track all the changes
    > made to the database since last full time backup, and it will backup
    > only those pages when do the incremental back up, and i was under the
    > impression when you issue 'incremental backup' db2 can figure pages
    > were changed in no time and backup those changes pretty fast.
    >
    > But in our, we have huge database, we want to implement the
    > incremental testing in our production environement. So we did a test
    > in our test environment, in the test evironment, it would normally
    > takes about one and half hours to complte the full database backup.
    > This is what i did,
    >
    > 1. Turned on 'TRACKMOD'
    >
    > 2. full database backup ( took around 1 and 1/2 hours )
    >
    > 3. deleted around huge amount of data from one table
    >
    > 4. ran a incremental backup command. Guess what? It took me almost the
    > same as full back up ( around 1 hour and 15 mins ), but the size of
    > the backup file is very small comparatively full database backup , but
    > the backup time between full and incremental is almost the same. I was
    > estimated that incremental would be finished within 5 mins.
    >
    >
    > The only advantage i am seeing using incremental back up is, small
    > backup file size.
    >
    > I am guessing that, even though 'TRACKMOD' is on, db2 is checking all
    > the data pages to see if that page is changed or not? Thats why its
    > taking so long as full database backup.
    >
    > Our db2 version 7.3, we are using both DMS and SMS tablespaces.
    >
    > any help will be greatly appreciated. Thanks
    >
    >
    > We have both SMS and DMS tablespaces on the database.
    Are you using version 7.2 with a fixpack level? There is no version 7.3. If
    some rows were deleted from every page when you deleted a "huge amount of
    data from one table," maybe that is why it is taking so long.


    Mark A Guest

  2. #2

    Default Re: DB2 incremental vs full back up

    Thanks mark, i really appreciate your response, but i dont think that
    delete modfied all the pages, let me put the same question in a
    differnt way,

    Lets assume that i have a database with 100,000 pages , and 100 pages
    has been modifed after full backup.

    Whats is really happening when you issue the incremental backup
    command?

    1. will db2 scan 100,000 pages and see if that page is changed or not
    and backup that page if changed , if not just skip that page and
    continue to check the rest of pages. If this the case, even if one
    page is changed , doest db2 still have to scan 100,000 pages to figure
    out which pages were changed? I was under the impression when you turn
    on "TRACKMOD" , it will keep track of changes as they occurs and
    stored the page information "somewhere" internally and so that db2 can
    get the list of pages that were changed by looking at the place where
    'TRACKMOD' stores them, I guess this is NOT the way db2 tracks pages
    which are changed, right?

    OR

    When you turn on TRACKMOD, all it does is, just update somewhere in
    the page header area that the page is changed, so db2 still have to
    scan all the pages to get the list of pages were changed?

    I am so confused now, Please explain me how does db2 make a list of
    pages were modified to perform the incremental backup?


    Many Thanks for your time.





    "Mark A" <maswitchboard.net> wrote in message news:<uyXQa.271$1D3.27541news.uswest.net>...
    > "Siva" <mail2sivaj> wrote in message
    > news:8a8e81a1.0307150952.610415b4posting.google.c om...
    > > What is real advantage of incremental back up ?
    > >
    > > I was under the impression, that 'TRACKMOD' will track all the changes
    > > made to the database since last full time backup, and it will backup
    > > only those pages when do the incremental back up, and i was under the
    > > impression when you issue 'incremental backup' db2 can figure pages
    > > were changed in no time and backup those changes pretty fast.
    > >
    > > But in our, we have huge database, we want to implement the
    > > incremental testing in our production environement. So we did a test
    > > in our test environment, in the test evironment, it would normally
    > > takes about one and half hours to complte the full database backup.
    > > This is what i did,
    > >
    > > 1. Turned on 'TRACKMOD'
    > >
    > > 2. full database backup ( took around 1 and 1/2 hours )
    > >
    > > 3. deleted around huge amount of data from one table
    > >
    > > 4. ran a incremental backup command. Guess what? It took me almost the
    > > same as full back up ( around 1 hour and 15 mins ), but the size of
    > > the backup file is very small comparatively full database backup , but
    > > the backup time between full and incremental is almost the same. I was
    > > estimated that incremental would be finished within 5 mins.
    > >
    > >
    > > The only advantage i am seeing using incremental back up is, small
    > > backup file size.
    > >
    > > I am guessing that, even though 'TRACKMOD' is on, db2 is checking all
    > > the data pages to see if that page is changed or not? Thats why its
    > > taking so long as full database backup.
    > >
    > > Our db2 version 7.3, we are using both DMS and SMS tablespaces.
    > >
    > > any help will be greatly appreciated. Thanks
    > >
    > >
    > > We have both SMS and DMS tablespaces on the database.
    >
    > Are you using version 7.2 with a fixpack level? There is no version 7.3. If
    > some rows were deleted from every page when you deleted a "huge amount of
    > data from one table," maybe that is why it is taking so long.
    Siva Guest

  3. #3

    Default Re: DB2 incremental vs full back up

    From the books:

    ------------------------------
    For SMS and DMS table spaces, the granularity of this tracking is at the
    table space level. In table space level tracking, a flag for each table
    space indicates whether or not there are pages in that table space that
    need to be backed up. If no pages in a table space need to be backed up,
    the backup operation can skip that table space altogether.
    ------------------------------

    This is saying that incremental, and delta, backups will scan all pages
    in a tablespace which has been modified since the previous backup. If
    there have been no modifications to a tablespace, none of the pages from
    that tablespace will be read by the BACKUP utility.

    Of course only the individual pages which have been modified will be
    written to the backup image.

    Depending on the architecture of your environment, and the ratios of
    pages and tablespaces which have been modified, incremental backups
    might be faster than non-incremental backups.

    Hope that clarifies things.
    kdr
    --
    ------------------------------------------------------------------
    Kelly D. Rodger IBM Canada
    DB2 UDB Backup and Recovery Toronto Lab
    ------------------------------------------------------------------

    Kelly D. Rodger Guest

  4. #4

    Default Re: DB2 incremental vs full back up



    "Kelly D. Rodger" wrote:
    > From the books:
    >
    > ------------------------------
    > For SMS and DMS table spaces, the granularity of this tracking is at the
    > table space level. In table space level tracking, a flag for each table
    > space indicates whether or not there are pages in that table space that
    > need to be backed up. If no pages in a table space need to be backed up,
    > the backup operation can skip that table space altogether.
    > ------------------------------
    >
    > This is saying that incremental, and delta, backups will scan all pages
    > in a tablespace which has been modified since the previous backup. If
    > there have been no modifications to a tablespace, none of the pages from
    > that tablespace will be read by the BACKUP utility.
    >
    > Of course only the individual pages which have been modified will be
    > written to the backup image.
    >
    > Depending on the architecture of your environment, and the ratios of
    > pages and tablespaces which have been modified, incremental backups
    > might be faster than non-incremental backups.
    >
    > Hope that clarifies things.
    > kdr
    > --
    > ------------------------------------------------------------------
    > Kelly D. Rodger IBM Canada
    > DB2 UDB Backup and Recovery Toronto Lab
    > ------------------------------------------------------------------
    This explains a lot!

    I ever did an incremental backup db testing for one of my customer.
    We have a database, the db size is about 20G, we defined a couple of DMS and
    SMS tablespaces. I created two tables in two DMS tablespaces. One of the
    table is the copy of another one. This two tablespaces - let's say BigSpace
    and SmallSpace, the total space for the BigSpace is 40G, for the SmallSpace
    is 4G.

    Take a full offline backup of the database, it took us nearly 7m.
    Did some Delete/Update only on the table in the BigSpace, then took a
    offline db incremental backup, which took me nearly 6m.

    If I only did the same change on the table in the SmallSpace, then took a
    offline db incremental backup, this time the backup only took us about
    0m40s.

    Regards,
    FRX

    Fan Ruo Xin Guest

  5. #5

    Default Re: DB2 incremental vs full back up

    Joachim Müller <j.muellerdouglas-informatik.de> wrote:
    > So, we have the problem that the full backup ist approximate the same
    > as the incremental backup.
    That's right. The Incremental Backup feature was designed to save space,
    not time. There are a few cases where incremental backups are faster
    than the equivalent full backups, but even then they're not tremendously
    faster.

    dave
    David Mooney Guest

  6. #6

    Default Re: DB2 incremental vs full back up

    You can speed up your BACKUP by using with NUM_BUFFERS option of the
    backup command for a given database(whether it is incremental or
    offline).

    I have decreased the backup time nearly 60% by using 6 buffers...

    Cheers....
    Shashi Mannepalli


    David Mooney <dmmvnet.ibm.com> wrote in message news:<bf624g$o33$1hanover.torolab.ibm.com>...
    > Joachim Müller <j.muellerdouglas-informatik.de> wrote:
    > > So, we have the problem that the full backup ist approximate the same
    > > as the incremental backup.
    >
    > That's right. The Incremental Backup feature was designed to save space,
    > not time. There are a few cases where incremental backups are faster
    > than the equivalent full backups, but even then they're not tremendously
    > faster.
    >
    > dave
    shashi b mannepalli Guest

Similar Threads

  1. incremental numbering
    By Enrique_Gomez@adobeforums.com in forum Adobe Illustrator Windows
    Replies: 1
    Last Post: June 19th, 02:08 PM
  2. ftp settings for incremental update
    By Todd Hatfield in forum Web Design
    Replies: 4
    Last Post: June 16th, 02:55 AM
  3. Incremental backups?
    By Ryan Ashline in forum Linux Setup, Configuration & Administration
    Replies: 12
    Last Post: September 22nd, 12:44 PM
  4. Play video full screen & back to 800x600 at end?
    By Cool Jools webforumsuser@macromedia.com in forum Macromedia Director Lingo
    Replies: 1
    Last Post: September 11th, 12:53 PM
  5. nfs incremental backups problem
    By Nicholas Dronen in forum AIX
    Replies: 1
    Last Post: August 5th, 07:57 PM

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139