IBM Mainframe Forum Index
 
Log In
 
IBM Mainframe Forum Index Mainframe: Search IBM Mainframe Forum: FAQ Register
 

What is the use of SYSDA,12


IBM Mainframe Forums -> JCL & VSAM
Post new topic   Reply to topic
View previous topic :: View next topic  
Author Message
sasikumar1984

Active User


Joined: 02 Jul 2007
Posts: 109
Location: Chennai - India

PostPosted: Wed Oct 31, 2007 5:03 pm
Reply with quote

Hi all,

Can anyone tell me what is the use of SYSDA,12

sysda,12 - Sysda is temp dataset... pls tell me what is mean by multi pack????

Regards,
Sasi.K
Back to top
View user's profile Send private message
Aaru

Senior Member


Joined: 03 Jul 2007
Posts: 1287
Location: Chennai, India

PostPosted: Wed Oct 31, 2007 5:50 pm
Reply with quote

sasikumar,

Quote:
Can anyone tell me what is the use of SYSDA


We usually specify UNIT=SYSDA in our JCL's while creating datasets.

This refers to the direct access devices which is our DASD.
Back to top
View user's profile Send private message
enrico-sorichetti

Superior Member


Joined: 14 Mar 2007
Posts: 10888
Location: italy

PostPosted: Wed Oct 31, 2007 6:00 pm
Reply with quote

You will find answers to your doubts here


OS/390 V2R9.0 MVS JCL User's Guide
http://publibz.boulder.ibm.com/cgi-bin/bookmgr_OS390/BOOKS/IEA1B530/CCONTENTS?SHELF=IEA1BK37&DN=GC28-1758-07&DT=20000118153249

and here :
OS/390 V2R9.0 MVS JCL Reference
http://publibz.boulder.ibm.com/cgi-bin/bookmgr_OS390/BOOKS/IEA1B630/CCONTENTS?SHELF=IEA1BK37&DN=GC28-1757-08&DT=20000118181113


if You want to look at more recent manuals start from
http://www-03.ibm.com/servers/eserver/zseries/zos/bkserv/
Back to top
View user's profile Send private message
mftrigger

New User


Joined: 18 Feb 2006
Posts: 23
Location: chennai

PostPosted: Wed Oct 31, 2007 6:10 pm
Reply with quote

UNIT=(SYSDA,N) refers to the N number of volumes to be allocated for that dataset.

I suppose the Multi pack data set is the same as multi volume dataset.
Back to top
View user's profile Send private message
sasikumar1984

Active User


Joined: 02 Jul 2007
Posts: 109
Location: Chennai - India

PostPosted: Thu Nov 01, 2007 7:53 am
Reply with quote

hi,

Can anyone tell me how to find the total space occupied by the dataset???


is it like Lrecel * no of Records

Eg: if the DS contains 100 records and Lrecel is 289. the total space occupied by the DS is 100*289?????

i think what i am telling is wrong... pls correct me...

Regards,
Sasikumar.K
Back to top
View user's profile Send private message
dick scherrer

Moderator Emeritus


Joined: 23 Nov 2006
Posts: 19243
Location: Inside the Matrix

PostPosted: Thu Nov 01, 2007 8:46 am
Reply with quote

Hello,

You can find the total space used using tso/ispf (usually 3.4).

When you list the dataset(s), type an I, press ent4er, and the system will show you space allocated and used - this will not work for vsam files (unless your system has add-on products to deal with vsam).

Your calculation will show you how many bytes are needed for the data, but that number is not exactly the same as the space requirement.
Back to top
View user's profile Send private message
sasikumar1984

Active User


Joined: 02 Jul 2007
Posts: 109
Location: Chennai - India

PostPosted: Thu Nov 01, 2007 10:18 am
Reply with quote

Hi dick,

thanks for ur reply..

Can you tell me what exactly SYSDA,12 means????? i heard it is called muplti pack... what it means????

sometimes we give UNIT=SYSDA. it is for creating a temporary DS.

As you said we can see how much a DS space by entering I infront of the DS in TSO/ISPF. But how that calculation has come???? i like to know that...

Please clear my doubts....

Regards,
Sasikumar.K
Back to top
View user's profile Send private message
Binaya

New User


Joined: 03 Jul 2007
Posts: 77
Location: Hyderabad

PostPosted: Thu Nov 01, 2007 10:25 am
Reply with quote

SYSDA,12 means it can span accross 12 disks. Means If the space is not available in 1 disk it will search for upto 12 disks. Its not necessarly for temporary DS.

[
Can you tell me what exactly SYSDA,12 means????? i heard it is called muplti pack... what it means????

sometimes we give UNIT=SYSDA. it is for creating a temporary DS.

]
Back to top
View user's profile Send private message
sasikumar1984

Active User


Joined: 02 Jul 2007
Posts: 109
Location: Chennai - India

PostPosted: Thu Nov 01, 2007 10:39 am
Reply with quote

Hi Binaya,

Thanks for ur response...

So for allocating DS in disks, UNIT=SYSDA,12 keeps searching upto 12 different disks rite.. is this concept is called Multi Pack????

So if we give simply UNIT=SYSDA, it will search only one disk????

Regards,
Sasikumar.K
Back to top
View user's profile Send private message
Binaya

New User


Joined: 03 Jul 2007
Posts: 77
Location: Hyderabad

PostPosted: Thu Nov 01, 2007 12:21 pm
Reply with quote

Not sure about Multi Pack phenomenon.

But giving simply UNIT=SYSDA, it will search only one disk
Back to top
View user's profile Send private message
Binaya

New User


Joined: 03 Jul 2007
Posts: 77
Location: Hyderabad

PostPosted: Thu Nov 01, 2007 1:34 pm
Reply with quote

Sorry, It should be "it can span accross 12 volumes"
Back to top
View user's profile Send private message
dick scherrer

Moderator Emeritus


Joined: 23 Nov 2006
Posts: 19243
Location: Inside the Matrix

PostPosted: Thu Nov 01, 2007 7:36 pm
Reply with quote

Hello,

Often the needed space is not available on the first volume assigned by the UNIT= parameter. Specifying UNIT=(dev,n) will allow allocation to use (span) up to n volumes to meet the space requirement.

Quote:
it is for creating a temporary DS.
This is a site-specific "rule". On many systems SYSDA also contains production, lng-term datasets.

In the "old" days, disk was removable media. The "drive" was similar to the cd/dvd drives in your desktop. The data was stored on "dick packs". There was no permanent drives - even the system residence (SYSRES) and spool packs were removable (usually, they were not, but could be if necessary). As you stack your cd/dvd's near your pc, we stacked disk packs near the dis drives. Disk packs were much cheaper than drives, so scheduling which data would be "online" at any one time coiuld become a challange.

A "dasd volume" and a "disk pack" are the same thing these days.
Back to top
View user's profile Send private message
sasikumar1984

Active User


Joined: 02 Jul 2007
Posts: 109
Location: Chennai - India

PostPosted: Sun Nov 04, 2007 8:14 am
Reply with quote

Hi Dick,

Thanks for you reply.. I still need answer for my query...

We can see how much a DS space by entering I infront of the DS in TSO/ISPF. But how that calculation has come???? i like to know that...

Can you please explain this...

Regards,
Sasikumar.K
Back to top
View user's profile Send private message
dick scherrer

Moderator Emeritus


Joined: 23 Nov 2006
Posts: 19243
Location: Inside the Matrix

PostPosted: Sun Nov 04, 2007 9:50 am
Reply with quote

Hello Sasikumar,

Quote:
But how that calculation has come????


What you see in 3.4 is not a calculation - it is the actual space allocated and in use for the dataset.

If i've misunderstood the question, please clarify.
Back to top
View user's profile Send private message
sasikumar1984

Active User


Joined: 02 Jul 2007
Posts: 109
Location: Chennai - India

PostPosted: Sun Nov 04, 2007 10:16 am
Reply with quote

Hi Dick,

Ok, i agree its the actual space utilised by the Dataset...

I would like to know is it possible to estimate the actual space will be occupied by a datset if we know Lrecl, No of records, Blocksize and all the related information for creating the dataset.

Regards,
Sasikumar.K
Back to top
View user's profile Send private message
dick scherrer

Moderator Emeritus


Joined: 23 Nov 2006
Posts: 19243
Location: Inside the Matrix

PostPosted: Sun Nov 04, 2007 10:42 am
Reply with quote

Hello Sasikumar,

To calculate space required, you use the number of records and their length. From lrecl, you will get a blksize (this will be done automatically by the system or your storage management people can tell you how blksize is determined for your system and dasd).

Once you know the blksize, you can calculate how many blocks will be needed and this will be used to determine total space (usually cyls or trks). Again, it will be good to check with the storage management people as there are different dasd models in use today and they will know your system specifics.

You might also look in the forum as there have been other topics on how to calculate dasd space.
Back to top
View user's profile Send private message
sasikumar1984

Active User


Joined: 02 Jul 2007
Posts: 109
Location: Chennai - India

PostPosted: Sun Nov 04, 2007 10:55 am
Reply with quote

Thanks a lot Dick....

So Nice Of U....

Regards,
Sasikumar.K
Back to top
View user's profile Send private message
expat

Global Moderator


Joined: 14 Mar 2007
Posts: 8796
Location: Welsh Wales

PostPosted: Sun Nov 04, 2007 2:07 pm
Reply with quote

Search the forum. I have lost count of the number of times that I have given the formula for space calculation on this forum.
Back to top
View user's profile Send private message
dick scherrer

Moderator Emeritus


Joined: 23 Nov 2006
Posts: 19243
Location: Inside the Matrix

PostPosted: Mon Nov 05, 2007 8:19 am
Reply with quote

You're welcome - we're here if there are questions icon_smile.gif
Back to top
View user's profile Send private message
View previous topic :: :: View next topic  
Post new topic   Reply to topic View Bookmarks
All times are GMT + 6 Hours
Forum Index -> JCL & VSAM

 


Similar Topics
Topic Forum Replies
No new posts SYSDA - how to make it point somewher... JCL & VSAM 19
No new posts Peformace issues for UNIT=(SYSDA,2) w... JCL & VSAM 5
No new posts Primary and Secondary Space allocatio... All Other Mainframe Topics 2
No new posts Difference between UNIT=SYSDA and UNI... JCL & VSAM 3
No new posts Can anybody provide more information ... Mainframe Interview Questions 1
Search our Forums:

Back to Top