how to convert cylinders to megabytes ??
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#1: how to convert cylinders to megabytes ?? Author: vak255 PostPosted: Fri May 04, 2007 3:08 am
    —
I like to know, how to convert cylinders to megabytes
and Track to Megabyte conversion?



Code:

XXSORTOUT  DD DSN=DEAA11A.SWARS(+1),           
XX            DISP=(NEW,CATLG,CATLG),                   
XX            SPACE=(CYL,(2500,500),RLSE),VOL=(,,,10), 
XX            UNIT=SYSDA,                               
XX            MGMTCLAS=MC0030,                         
XX            DCB=(PSDSCB,DSORG=PS,RECFM=VB,LRECL=2004)


Data Set:   DEAA11A.SWARS                                     
 On Volume:  PNH002                                                             
                                                                               
         DCB Attributes: Dsorg: PS  Recfm= VB  Lrecl= 2004  Blksize= 27998     
                                                                               
         Created By: UNKNOWN  on 07123                Management Class: MC0030 
 Last Referenced By: IBMOSVS2 on 07123                      Data Class: DCSTD   
   Last Modified On:                                     Storage Class: SCPRIME



   Tracks Allocated: 60000  Cyls: 4000             
        Tracks Used: 60000  Cyls: 4000   100%       
     Nbr Of Extents: 6                             
    Secondary Space: 500 Cyls     



Here, I have coded RLSE parameter for DEAA11A.SWARS but still it shows 100% used.
How CYL,(2500,500) is shown as Tracks Used: 60000 Cyls: 4000

Any help is greatly appreciated!!

#2:  Author: expatLocation: Welsh Wales PostPosted: Fri May 04, 2007 3:19 am
    —
Quote:
I like to know, how to convert cylinders to megabytes
and Track to Megabyte conversion?

I think I see the logic behind your request, but, the DASD allocation routines will convert whatever space allocation you have specified, records, Kb, Mb into either cylinder or track allocations. Personally I never bother.

Quote:
Here, I have coded RLSE parameter for DEAA11A.SWARS but still it shows 100% used.
How CYL,(2500,500) is shown as Tracks Used: 60000 Cyls: 4000

If you think about it, it would show 100% used. You have specified via RLSE that any unused space is released, so if all of the allocated space is being used it would be 100%.

#3:  Author: Nic CloustonLocation: At Home PostPosted: Fri May 04, 2007 3:21 am
    —
If you use RLSE all unused space ie released therefore what is left allocated is 100% used - no wasted space. you need the 3390 ref card or similar to find out how many records of that LRECL fit on a track and work from there.

#4:  Author: expatLocation: Welsh Wales PostPosted: Fri May 04, 2007 3:40 am
    —
Interesting JCL code too ..............
Code:

XXSORTOUT  DD DSN=DEAA11A.SWARS(+1),           
XX            DISP=(NEW,CATLG,CATLG),                   
XX            SPACE=(CYL,(2500,500),RLSE),VOL=(,,,10), 
XX            UNIT=SYSDA,                               
XX            MGMTCLAS=MC0030,                         
XX            DCB=(PSDSCB,DSORG=PS,RECFM=VB,LRECL=2004)

If you storage group have set up SMS properly, there is no longer a need to code JCL in the prehistoric manner.

I would have coded ...
Code:

XXSORTOUT  DD DSN=DEAA11A.SWARS(+1),           
XX            DISP=(NEW,CATLG,CATLG),                   
XX            SPACE=(CYL,(2500,500),RLSE),VOL=(,,,10), 
XX            RECFM=VB,LRECL=2004

If SMS assigns a DATACLAS to EVERY dataset, be it SMS managed or not, DASD or tape, then there is no need to code a model or pattern DSCB. What are the attributes of this model, if they are equally as archaic then maybe the BLKSIZE would be LRECL+4 which would waste a lot of DASD space.

RECFM and LRECL are parameters in their own right and no longer need to be coded as sub parameters of the DCB field.

#5:  Author: vak255 PostPosted: Fri May 04, 2007 4:38 am
    —
Thanks for the reponse.

Quote:

RECFM and LRECL are parameters in their own right and no longer need to be coded as sub parameters of the DCB field.

expat, do you mean the DCB parameters are not required.

Quote:

BLKSIZE would be LRECL+4 which would waste a lot of DASD space.


I have not coded BLKSIZE, so it is SMS managed. Sorry I could not get you.

#6:  Author: expatLocation: Welsh Wales PostPosted: Fri May 04, 2007 4:56 am
    —
If you look at what I would have coded you can see that I did not include DCB=

As I said, IF your SMS environment is set up correctly then you do not need the model DSCB in your JCL.

The model or pattern DSCB that you have specified may have an inefficient blocksize coded, and because you had coded DCB=(PSDSCB the blocksize used for your dataset would be the same as that of PSDSCB.

#7:  Author: Nic CloustonLocation: At Home PostPosted: Fri May 04, 2007 4:58 am
    —
Quote:

do you mean the DCB parameters are not required

Yes - as per the manual. For several years now (since the mid 90s?) LRECL, RECFM and BLKSIZE (and probably others) are stand-alone parameters i.e. they do not need to be coded as sub-parameters of DCB

#8:  Author: kolusuLocation: San Jose PostPosted: Fri May 04, 2007 8:51 am
    —
A 3390-n device has a capacity of 56,664 bytes per track,of which 55,996 bytes are accessible by applications programmers. And 1 cylinder is 15 tracks.

So let us take the accessible bytes in a track which is 55,996.
Code:

1 Cylinder = 55,996 * 15  =  839,940 bytes.

so 1000 cylinders = 839,940 * 1000   

1 Megabyte =  1,048,576 (2 to the 20th power) bytes.

1000 cylinders = (839,940 * 1000 ) / 1,048,576  = 801.029 MB

1 terabyte =  2 to the 40th power or approximately a thousand billion bytes (that is, a thousand gigabytes).

1000 cylinders = (839,940 * 1000 ) / (1,048,576 * 1,048,576 )  = .000763 Terabytes

Hope this helps...

Cheers

Kolusu

#9:  Author: vak255 PostPosted: Fri May 04, 2007 8:53 am
    —
Thanks a ton.

Can anyone help me with cylinder/track to Megabyte conversion.

#10:  Author: Nic CloustonLocation: At Home PostPosted: Fri May 04, 2007 8:58 am
    —
Yeah - Kolusu has just posted it

#11:  Author: vak255 PostPosted: Fri May 04, 2007 9:16 am
    —
Disk space is measured in cylinders for CMS, in megabytes for UNIX, and in tracks for MVS. For an approximate conversion between cylinders and megabytes, use the formula "1 cylinder = 600 KB" (1 KB = 1024 bytes, 1024 KB = 1 MB). For conversion between cylinders and tracks, use the formula "1 cylinder = 15 tracks".

The megabyte formula will actually provide more UNIX disk space than needed. The true number of bytes per cylinder varies as a result of arbitrary choices made by you when creating the files on CMS or when formatting the minidisk.

The following table lists some representative disk quotas in cylinders and in megabytes

1 cyl = 0.6 MB --- CMS default
5 cyls = 3 MB
10 cyls = 6 MB
17 cyls = 10 MB --- UNIX default
50 cyls = 29 MB
100 cyls = 59 MB
171 cyls = 100 MB
341 cyls = 200 MB

Here I got it from IMB website, still I am not sure what to apply for MVS. Any comments...

#12:  Author: kolusuLocation: San Jose PostPosted: Fri May 04, 2007 9:35 am
    —
vak255,

Did you miss reading my post?

Kolusu

#13:  Author: Nic CloustonLocation: At Home PostPosted: Fri May 04, 2007 9:38 am
    —
MVS uses cyls, tracks, blocks u-name-it. I should think CMS (which I think runs under VM) uses probably the same. Never tried UNIX allocations

but as Koluso said 55996 bytes per track, 15 tracks per cyl number of cyls per 3390 depends on version of 3390.

#14:  Author: vak255 PostPosted: Mon May 07, 2007 1:54 am
    —
Thank you so much for all the help!!!

#15:  Author: Bill DennisLocation: Iowa, USA PostPosted: Mon May 07, 2007 8:13 am
    —
Be mindful that the actual usable bytes per track depends greatly on physical blocksize written. Small blocks waste alot of space on each track due to the architecture.

Here is a link to the 3390 Device Capacity chart showing bytes used at various blksizes:
http://publibz.boulder.ibm.com/cgi-bin/bookmgr_OS390/BOOKS/am3u1001/B.1.2



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