Help needed for Space calculations for Incr. Image copy

James Campbell

Help needed for Space calculations for Incr. Image copy
I am having problems calculating the DASD space required for Incremental
image copies. In using the data from the report below and using the formula

(changed-pages * nKB-Pages) / 1mb = Total DASD needed to take the
incremental
(nKB = sysibm.systablespace pgsize)

using the first partition listed - for example: ((78*4) / 1024000 ) =
.0003046 MB

I come up with less then one MB to backup the dataset but even allocating 5
MB for the dataset to hold the backup I get a B37-04 abend. Am I missing
some overhead pages that get backed up as well or is this report
in-accurate.

When I run a COPY with the REPORTONLY option I get a report that looks like
this

4KB CHANGED PERCENT OF

DBNAME TSNAME DSNUM PAGES PAGES CHANGED PAGES
ICTYPE
-------- -------- ----- ------------- ------------- -------------
------
DBNAME XXX02 1 81,819 78 0.09

DBNAME XXX02 2 84,091 55 0.06

DBNAME XXX02 3 81,791 63 0.07

DBNAME XXX02 4 81,525 81 0.09

DBNAME XXX02 5 82,621 79 0.09

DBNAME XXX02 6 80,838 88 0.10

DBNAME XXX02 7 84,381 63 0.07

DBNAME XXX02 8 80,570 83 0.10

DBNAME XXX02 9 86,151 72 0.08

DBNAME XXX02 10 83,069 74 0.08

DBNAME XXX02 ALL 826,856 736 0.08 I










James (Jim) Campbell
Sr. Analyst &
Test Systems Coordinator
CNF ADTECH
Phone: (503) 450-4839
Fax: (503) 450-3629
Email: [login to unmask email] <mailto:[login to unmask email]>



Eric Pearson

Re: Help needed for Space calculations for Incr. Image copy
(in response to James Campbell)
James,
I think you need to change 78*4 to 78*4096. 4k per page, not 4 bytes per
page.

regards,

eric pearson
NS ITO Database Support


-----Original Message-----
From: Campbell, James B - CNF [mailto:[login to unmask email]
Sent: Monday, March 12, 2001 12:47 PM
To: [login to unmask email]
Subject: Help needed for Space calculations for Incr. Image copy


I am having problems calculating the DASD space required for Incremental
image copies. In using the data from the report below and using the formula

(changed-pages * nKB-Pages) / 1mb = Total DASD needed to take the
incremental
(nKB = sysibm.systablespace pgsize)

using the first partition listed - for example: ((78*4) / 1024000 ) =
.0003046 MB

I come up with less then one MB to backup the dataset but even allocating 5
MB for the dataset to hold the backup I get a B37-04 abend. Am I missing
some overhead pages that get backed up as well or is this report
in-accurate.

When I run a COPY with the REPORTONLY option I get a report that looks like
this

4KB CHANGED PERCENT OF

DBNAME TSNAME DSNUM PAGES PAGES CHANGED PAGES
ICTYPE
-------- -------- ----- ------------- ------------- -------------
------
DBNAME XXX02 1 81,819 78 0.09

DBNAME XXX02 2 84,091 55 0.06

DBNAME XXX02 3 81,791 63 0.07

DBNAME XXX02 4 81,525 81 0.09

DBNAME XXX02 5 82,621 79 0.09

DBNAME XXX02 6 80,838 88 0.10

DBNAME XXX02 7 84,381 63 0.07

DBNAME XXX02 8 80,570 83 0.10

DBNAME XXX02 9 86,151 72 0.08

DBNAME XXX02 10 83,069 74 0.08

DBNAME XXX02 ALL 826,856 736 0.08 I










James (Jim) Campbell
Sr. Analyst &
Test Systems Coordinator
CNF ADTECH
Phone: (503) 450-4839
Fax: (503) 450-3629
Email: [login to unmask email] <mailto:[login to unmask email]>








James Campbell

Re: Help needed for Space calculations for Incr. Image copy
(in response to Eric Pearson)
Sorry I miss-stated my calculation its as follows - ((78*4)*1024) / 1024000

James (Jim) Campbell
Sr. Analyst &
Test Systems Coordinator
CNF ADTECH
Phone: (503) 450-4839
Fax: (503) 450-3629
Email: [login to unmask email] <mailto:[login to unmask email]>


-----Original Message-----
From: Pearson, Eric L, [SMTP:[login to unmask email]
Sent: Monday, March 12, 2001 10:22 AM
To: [login to unmask email]
Subject: Re: Help needed for Space calculations for Incr.
Image copy

James,
I think you need to change 78*4 to 78*4096. 4k per page, not 4 bytes
per
page.

regards,

eric pearson
NS ITO Database Support


-----Original Message-----
From: Campbell, James B - CNF [mailto:[login to unmask email]
Sent: Monday, March 12, 2001 12:47 PM
To: [login to unmask email]
Subject: Help needed for Space calculations for Incr. Image copy


I am having problems calculating the DASD space required for
Incremental
image copies. In using the data from the report below and using the
formula

(changed-pages * nKB-Pages) / 1mb = Total DASD needed to take the
incremental
(nKB = sysibm.systablespace
pgsize)

using the first partition listed - for example: ((78*4)*1024) /
1024000 ) =
.0003046 MB

I come up with less then one MB to backup the dataset but even
allocating 5
MB for the dataset to hold the backup I get a B37-04 abend. Am I
missing
some overhead pages that get backed up as well or is this report
in-accurate.

When I run a COPY with the REPORTONLY option I get a report that
looks like
this

4KB CHANGED PERCENT OF

DBNAME TSNAME DSNUM PAGES PAGES CHANGED
PAGES
ICTYPE
-------- -------- ----- ------------- -------------
-------------
------
DBNAME XXX02 1 81,819 78
0.09

DBNAME XXX02 2 84,091 55
0.06

DBNAME XXX02 3 81,791 63
0.07

DBNAME XXX02 4 81,525 81
0.09

DBNAME XXX02 5 82,621 79
0.09

DBNAME XXX02 6 80,838 88
0.10

DBNAME XXX02 7 84,381 63
0.07

DBNAME XXX02 8 80,570 83
0.10

DBNAME XXX02 9 86,151 72
0.08

DBNAME XXX02 10 83,069 74
0.08

DBNAME XXX02 ALL 826,856 736
0.08 I










James (Jim) Campbell
Sr. Analyst &
Test Systems Coordinator
CNF ADTECH
Phone: (503) 450-4839
Fax: (503) 450-3629
Email: [login to unmask email] <mailto:[login to unmask email]>



visit the
DB2-L webpage at http://www.ryci.com/db2-l. The owners of the list
can be





can



jane mike

Space calculations
(in response to James Campbell)
Hi

I defined a Tablespace with PRIQTY 12 and SECQTY 12. Only one table defined
in that.

I started to insert rows in that table, after inserting more than 60 rows
(record length 460), this is nearly 10 pages. As per our definition of
tablespace, it suppose to extend to another track, but it did do that thoufh
i specified 12 (equal to 3 pages) as priqty. Also i inserted another 100
rows totaly 160 rows. The dataset size extended to 2 more tracks.

When will the track extend..? extended only finishing 10/12 pages
(3380/3390)..? if so, giving less SECQTY is meaningless...? is it..?

pls clarify me..

thanks
Jane


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Gregory Palgrave

Re: Space calculations
(in response to jane mike)
Jane,

Even though you specify a PRIQTY 12, the underlying MVS file alloaction is a
minimum of 1 TRACK - assuming you have 3390 DASD, this will be about 56K to
MVS and ~48K (or 12 pages) for DB2. For 3380 it's around 48K for MVS and
40K (10 pages) for DB2.

Specifying a PRIQTY or SECQTY less than the track size (48K/3390) is pretty
much a waste of time.

Check the doco for when the extends occur - I don't recall at the moment
(due to Xmas lunch :) ) but when the current allocated extent becomes x
percent full or something like that, it will take the next extent.

Cheers - and Merry Christmas,


Greg Palgrave
Database Administrator
Unisys West

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-----Original Message-----
From: jane mike [mailto:[login to unmask email]
Sent: Friday, 21 December 2001 13:50
To: [login to unmask email]
Subject: Space calculations


Hi

I defined a Tablespace with PRIQTY 12 and SECQTY 12. Only one table defined
in that.

I started to insert rows in that table, after inserting more than 60 rows
(record length 460), this is nearly 10 pages. As per our definition of
tablespace, it suppose to extend to another track, but it did do that thoufh
i specified 12 (equal to 3 pages) as priqty. Also i inserted another 100
rows totaly 160 rows. The dataset size extended to 2 more tracks.

When will the track extend..? extended only finishing 10/12 pages
(3380/3390)..? if so, giving less SECQTY is meaningless...? is it..?

pls clarify me..

thanks
Jane



Hanne Lyssand

Re: Space calculations
(in response to Gregory Palgrave)
An extent of a dataset can not occupie less than one trk. Whith a 3390
volume and 4kb pagesize you just as well uses 48 PRIQTY and 48 SECQTY who
is one trk primary and one trk for each extent. If you use less it make no
practical differense.

Best regards
Hanne



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Michael Ebert

Re: Space calculations
(in response to Hanne Lyssand)
Hi Jane,

as far as I know, DB2 will only allocate datasets either by track
(multiple of 48) or cylinder (multiple of 720=15 tracks). I think it uses
TRK if either PRIQTY or SECQTY is below 720, CYL otherwise; I've seen this
somewhere but don't remember exactly where (might be SQL Ref, syntax for
CREATE TS or the Admin Guide or...). I've made it a rule to allocate
TSs/Indexes in multiples of 48 (if very small) or 720 (otherwise), and
having PRIQTY and SECQTY in the same allocation units (i.e. either both
<720 or both >=720). If a dataset starts very small and then grows, I
update PRI/SECQTY to reflect that growth, and change the allocation unit
of the VSAM file by moving it with ADRDSSU with the TGTALLOC(CYL) option.
On re-reading your posting, I've grown unsure of what exactly you want to
know... hope my response helps you some.

Dr. Michael Ebert
DB2 Database Administrator
aMaDEUS Data Processing
Erding / Munich, Germany



Hi

I defined a Tablespace with PRIQTY 12 and SECQTY 12. Only one table
defined
in that.

I started to insert rows in that table, after inserting more than 60 rows
(record length 460), this is nearly 10 pages. As per our definition of
tablespace, it suppose to extend to another track, but it did do that
thoufh
i specified 12 (equal to 3 pages) as priqty. Also i inserted another 100
rows totaly 160 rows. The dataset size extended to 2 more tracks.

When will the track extend..? extended only finishing 10/12 pages
(3380/3390)..? if so, giving less SECQTY is meaningless...? is it..?

pls clarify me..

thanks
Jane

sushant dash

Re: Space calculations
(in response to Michael Ebert)
The value of X percent is 50 percent. When DB2 marks that 50 percent of a extent is full it allocates another extent. This was the practice some years back. Whether any improvement with new versions couyld differ my answer. We need to verify with the experts.

Thanks
Dash

On Fri, 21 Dec 2001 Palgrave, Greg wrote :
> Jane,
>
> Even though you specify a PRIQTY 12, the underlying MVS
> file alloaction is a
> minimum of 1 TRACK - assuming you have 3390 DASD, this
> will be about 56K to
> MVS and ~48K (or 12 pages) for DB2. For 3380 it's
> around 48K for MVS and
> 40K (10 pages) for DB2.
>
> Specifying a PRIQTY or SECQTY less than the track size
> (48K/3390) is pretty
> much a waste of time.
>
> Check the doco for when the extends occur - I don't
> recall at the moment
> (due to Xmas lunch :) ) but when the current allocated
> extent becomes x
> percent full or something like that, it will take the
> next extent.
>
> Cheers - and Merry Christmas,
>
>
> Greg Palgrave
> Database Administrator
> Unisys West
>
> The information in this email and in any attachments is
> confidential and
> intended solely for the attention and use of the named
> addressee(s). This
> information may be subject to legal professional or
> other privilege or may
> otherwise be protected by work product immunity or
> other legal rules. It
> must not be disclosed to any person without our
> consent. If you are not the
> intended recipient, or a person responsible for
> delivering it to the
> intended recipient, you are not authorised to and must
> not disclose, copy,
> distribute, or retain this message or any part of it.
>
>
>
> -----Original Message-----
> From: jane mike [mailto:[login to unmask email]
> Sent: Friday, 21 December 2001 13:50
> To: [login to unmask email]
> Subject: Space calculations
>
>
> Hi
>
> I defined a Tablespace with PRIQTY 12 and SECQTY 12.
> Only one table defined
> in that.
>
> I started to insert rows in that table, after inserting
> more than 60 rows
> (record length 460), this is nearly 10 pages. As per
> our definition of
> tablespace, it suppose to extend to another track, but
> it did do that thoufh
> i specified 12 (equal to 3 pages) as priqty. Also i
> inserted another 100
> rows totaly 160 rows. The dataset size extended to 2
> more tracks.
>
> When will the track extend..? extended only finishing
> 10/12 pages
> (3380/3390)..? if so, giving less SECQTY is
> meaningless...? is it..?
>
> pls clarify me..
>
> thanks
> Jane
>
>
> To change your subscription options or to cancel your
> subscription visit the DB2-L webpage at
> http://www.ryci.com/db2-l. The owners of the list can
>





Isaac Yassin

Re: Space calculations
(in response to sushant dash)
Hi,
DB2 Admin. - again ....

DB2 extends data sets when:

v The requested space exceeds the remaining space

v 10 percent of the smaller allocation space (but not over 10 allocation units such

as tracks or cylinders)exceeds the remaining space .....



Wonderful reading material ...



Isaac Yassin
[login to unmask email]
----- Original Message -----
From: "jane mike" <[login to unmask email]>
Newsgroups: bit.listserv.db2-l
To: <[login to unmask email]>
Sent: Friday, December 21, 2001 7:49 AM
Subject: Space calculations


> Hi
>
> I defined a Tablespace with PRIQTY 12 and SECQTY 12. Only one table defined
> in that.
>
> I started to insert rows in that table, after inserting more than 60 rows
> (record length 460), this is nearly 10 pages. As per our definition of
> tablespace, it suppose to extend to another track, but it did do that thoufh
> i specified 12 (equal to 3 pages) as priqty. Also i inserted another 100
> rows totaly 160 rows. The dataset size extended to 2 more tracks.
>
> When will the track extend..? extended only finishing 10/12 pages
> (3380/3390)..? if so, giving less SECQTY is meaningless...? is it..?
>
> pls clarify me..
>
> thanks
> Jane
>
>
> _________________________________________________________________
> Get your FREE download of MSN Explorer at http://explorer.msn.com/intl.asp.
>
>
> DB2-L webpage at http://www.ryci.com/db2-l. The
owners of the list can
>



Michael Ebert

Re: Space calculations
(in response to Isaac Yassin)
Not true since at least V4. There's no problem getting a TS to 100% used.
As mentioned, there's a description somewhere on how and when DB2
allocates new extents. Maybe DB2 will format the next page (which may lead
to allocation of a new extent) if the current one is x% full; but this has
nothing to do with extents. I think it's most likely a myth.

Dr. Michael Ebert
DB2 Database Administrator
aMaDEUS Data Processing
Erding / Munich, Germany



The value of X percent is 50 percent. When DB2 marks that 50 percent of a
extent is full it allocates another extent. This was the practice some
years back. Whether any improvement with new versions couyld differ my
answer. We need to verify with the experts.

Thanks
Dash

On Fri, 21 Dec 2001 Palgrave, Greg wrote :
> Jane,
>
> Even though you specify a PRIQTY 12, the underlying MVS
> file alloaction is a
> minimum of 1 TRACK - assuming you have 3390 DASD, this
> will be about 56K to
> MVS and ~48K (or 12 pages) for DB2. For 3380 it's
> around 48K for MVS and
> 40K (10 pages) for DB2.
>
> Specifying a PRIQTY or SECQTY less than the track size
> (48K/3390) is pretty
> much a waste of time.
>
> Check the doco for when the extends occur - I don't
> recall at the moment
> (due to Xmas lunch :) ) but when the current allocated
> extent becomes x
> percent full or something like that, it will take the
> next extent.
>
> Cheers - and Merry Christmas,
>
>
> Greg Palgrave
> Database Administrator
> Unisys West