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What is the use of SYSDA,12

 
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sasikumar1984

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PostPosted: Wed Oct 31, 2007 5:03 pm    Post subject: What is the use of SYSDA,12
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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
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Aaru

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PostPosted: Wed Oct 31, 2007 5:50 pm    Post subject: Reply to: Multi pack??????
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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.
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enrico-sorichetti

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PostPosted: Wed Oct 31, 2007 6:00 pm    Post subject: Reply to: Multi pack??????
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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/
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mftrigger

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PostPosted: Wed Oct 31, 2007 6:10 pm    Post subject: Can anyone tell me what is the use of SYSDA,12
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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.
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sasikumar1984

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PostPosted: Thu Nov 01, 2007 7:53 am    Post subject: space occupied by the dataset
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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
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dick scherrer

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PostPosted: Thu Nov 01, 2007 8:46 am    Post subject:
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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.
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sasikumar1984

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PostPosted: Thu Nov 01, 2007 10:18 am    Post subject: sysda,12
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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
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Binaya

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PostPosted: Thu Nov 01, 2007 10:25 am    Post subject: Re: sysda,12
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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.

]
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sasikumar1984

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PostPosted: Thu Nov 01, 2007 10:39 am    Post subject: SYSDA,12
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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
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Binaya

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PostPosted: Thu Nov 01, 2007 12:21 pm    Post subject: Re: SYSDA,12
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Not sure about Multi Pack phenomenon.

But giving simply UNIT=SYSDA, it will search only one disk
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Binaya

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PostPosted: Thu Nov 01, 2007 1:34 pm    Post subject:
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Sorry, It should be "it can span accross 12 volumes"
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dick scherrer

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PostPosted: Thu Nov 01, 2007 7:36 pm    Post subject:
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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.
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sasikumar1984

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PostPosted: Sun Nov 04, 2007 8:14 am    Post subject: Hi
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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
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dick scherrer

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PostPosted: Sun Nov 04, 2007 9:50 am    Post subject:
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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.
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sasikumar1984

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PostPosted: Sun Nov 04, 2007 10:16 am    Post subject: hi
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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
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dick scherrer

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PostPosted: Sun Nov 04, 2007 10:42 am    Post subject:
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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.
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sasikumar1984

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PostPosted: Sun Nov 04, 2007 10:55 am    Post subject: hi
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Thanks a lot Dick....

So Nice Of U....

Regards,
Sasikumar.K
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expat

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PostPosted: Sun Nov 04, 2007 2:07 pm    Post subject:
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Search the forum. I have lost count of the number of times that I have given the formula for space calculation on this forum.
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dick scherrer

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PostPosted: Mon Nov 05, 2007 8:19 am    Post subject:
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You're welcome - we're here if there are questions icon_smile.gif
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