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Stripe sets, high watermark and restores

P: n/a
Hi,

I have some questions related to stripe sets that I'm hoping someone here
can answer.

1) What happens to stripe sets when doing a database restore? Do they stay
as is?

2) What happens to stripe sets when doing a redirect database restore? Will
a new tablespace map be created by this and thus override the existing
stripe sets?

3) From my current understanding, if I add a new stripe set the extent
numbering starts from the last extent in the previous stripe. So when data
is added it will still continue from the lowest available extent and go up
correct? And thus my new new stripe set will not receive data until the
lowest extent number available falls within this new stripe set correct?

4) Now if I have 1 stripe set which is 20MB (STRIPE 1), then I add another
stripe set of 10MB (STRIPE 2) and I load 25MB worth of data into this
tablespace. If I then increase STRIPE 1 (by extending the containers or
adding new containers to it) with 20MB. What will happen with the extent
numbering? Will this added on space in STRIPE 1 continue it's extent
numbering with the last extent number of STRIPE 2? So that for example I
have something like:

Before increasing STRIPE 1:
STRIPE 1: Extent 1 -> Extent 40
STRIPE 2: Extent 41 -> Extent 61

After increasing STRIPE 1:
STRIPE 1: Extent 1 -> Extent 40
STRIPE 1: Extent 62 -> Extent 102
STRIPE 2: Extent 41 -> Extent 61

Or will the extent number change so that I end up with:
STRIPE 1: Extent 1 -> Extent 40
STRIPE 1: Extent 41 -> Extent 81
STRIPE 2: Extent 82 -> Extent 102

In which case, the data that used to be between extent 41 and 61 is now
sitting between extent 82 and 102. If this is the case, then my high
watermark thus increases as well correct?
Thanks for the insight.
Nov 12 '05 #1
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P: n/a
See below in your note ###########

--
Pierre Saint-Jacques
SES Consultants Inc.
514-737-4515
"Erik Hendrix" <he**********@hotmail.com> a écrit dans le message de news:
1120171052.77034d4a14585d7e548c8865f3eeed5a@terane ws...
Hi,

I have some questions related to stripe sets that I'm hoping someone here
can answer.

1) What happens to stripe sets when doing a database restore? Do they stay
as is? ########### Yes. Restore brings the data in the same place it lifted it
from, For one, that way, the indexes do not have to be rebuilt in a restore
as the ponters have not moved. The data page is placed in its original
"relative" place (how far from pade 0 of the tablespace) 2) What happens to stripe sets when doing a redirect database restore?
Will
a new tablespace map be created by this and thus override the existing
stripe sets? ########### A redirected restore builds new containers. Each new container
must be as big as the high water mark of the old ones. The data within the
high water mark returns in the same "relative" place as where it was lifted
from. Stripe sets and maps could change as you could redirect and add one or
more NEW containers.
3) From my current understanding, if I add a new stripe set the extent
numbering starts from the last extent in the previous stripe. So when data
is added it will still continue from the lowest available extent and go up
correct? And thus my new new stripe set will not receive data until the
lowest extent number available falls within this new stripe set correct? ########### Adding as new stripe set is: alter tablespace.... begin new
stripe set...
You typically do that because you have no more space in the containers, you
need to add some and you do not want to rebalance. This makes the space
immediately available. If you space left in the old containers, I believe
db2 will use that before using the new stripe set, so you are correct.
If you use: alter tablespace ...
4) Now if I have 1 stripe set which is 20MB (STRIPE 1), then I add another
stripe set of 10MB (STRIPE 2) and I load 25MB worth of data into this
tablespace. If I then increase STRIPE 1 (by extending the containers or
adding new containers to it) with 20MB. What will happen with the extent
numbering? Will this added on space in STRIPE 1 continue it's extent
numbering with the last extent number of STRIPE 2? So that for example I
have something like: ########### If you add a new stripe, it must be defined in a new container.
No rebalance should happen.
As you extend Container 0 by ADD TO STRIPESET 1, you cause a rebalance of
the tablespace, so I believe that your Map and stripes will be different.
See following discussion in Docs. at:
http://publib.boulder.ibm.com/infoce...oc/welcome.htm
and look for: How containers are added.... in the search results column on
the left.
HTH, Pierre.
Before increasing STRIPE 1:
STRIPE 1: Extent 1 -> Extent 40 In Container 0
STRIPE 2: Extent 41 -> Extent 61 In Container 1, added with ..begin new
stripe set..

After increasing STRIPE 1: ############ No, I believe this is what
willhappen
STRIPE 1: Extent 1 -> Extent 40 STRIPE 1: Extent 1 ->
Extent 40, in Container 0
STRIPE 1: Extent 62 -> Extent 102 STRIPE 1: Extent 62 ->
Extent 102 in Container 1
STRIPE 2: Extent 41 -> Extent 61

Or will the extent number change so that I end up with:
STRIPE 1: Extent 1 -> Extent 40
STRIPE 1: Extent 41 -> Extent 81
STRIPE 2: Extent 82 -> Extent 102

In which case, the data that used to be between extent 41 and 61 is now
sitting between extent 82 and 102. If this is the case, then my high
watermark thus increases as well correct?
Thanks for the insight.


Nov 12 '05 #2

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