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  1. H390-MVS
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CKD, CCKD and CCKD64 devices

 

开云体育

Hi everybody

?

What are the real differences between these file formats?

CKD, CCKD and CCKD64

TIA

Jo?o

?

?

?

?


--
att.
Jo?o
 

CKD = uncompressed native with 32-bit pointers
CCKD = compressed native with 32-bit pointers
CCKD64 = compressed with 64-bit pointers

Otherwise, they are the same

Joe

On Mon, Apr 29, 2024 at 2:26?PM Jo?o Reginato via <jb.reginato=[email protected]> wrote:

Hi everybody

?

What are the real differences between these file formats?

CKD, CCKD and CCKD64

TIA

Jo?o

?

?

?

?


--
att.
Jo?o

 

Joe Monk wrote:
Jo?o Reginato wrote:

What are the real differences between these file formats?

CKD, CCKD and CCKD64
CKD = uncompressed native with 32-bit pointers
CCKD = compressed native with 32-bit pointers
CCKD64 = compressed with 64-bit pointers

Otherwise, they are the same
ALMOST correct. :)

CKD = uncompressed, period. There are no internal file format file pointers involved with accessing plain CKD files. Track data on plain CKD files are directly accessed (directly indexed): track number times track size (including overhead) equals the dasd file's seek address to the data for that track.

Whether the host operating system file pointers used to access file data is 32-bits or 64-bits depends solely on whether the host operating system itself supports 64-bit files and file access or not. Even older 32-bit versions of Windows support 64-bit files and 64-bit file access, since even older 32-bit versions of Windows (as well as the NTFS file system itself) support files larger than 4GB.

So *technically*, plain CKD files use 64-bit file pointers. It's just than the plain CKD file format does contain any file pointers at all anywhere in its data. Thus plain CKD files can access dasd volumes that can hold more than 4GB of data (e.g. 3390-9 or larger).

And *also* technically you should use the term "32/64-bit file-format FILE pointers", not just "32/64-bit pointers" for the reason already explained above.

But other than those admitted nit-picks, Joe is essentially correct.

For more detailed information, please refer to our README on the topic:

*

--
"Fish" (David B. Trout)
Software Development Laboratories

mail: fish@...
 

Fish wrote:

[...]
For more detailed information, please refer to our README on the topic:

*
390/hyperion/blob/master/readme/README.CCKD64.md
See also:

*

--
"Fish" (David B. Trout)
Software Development Laboratories

mail: fish@...
 

CCKD64 for some reason does not like to get tared and bzip2ed subsequently I can't make a reliable backup tar ball of the system when using CCKD64.? The problem did not exist with the plain cckd dasd image.


regards;

Rahim??



??



On Monday, April 29, 2024 at 02:26:20 PM CDT, Jo?o Reginato <jb.reginato@...> wrote:


Hi everybody

?

What are the real differences between these file formats?

CKD, CCKD and CCKD64

TIA

Jo?o

?

?

?

?


--
att.
Jo?o

 

开云体育

Ok,

?

Another related questions:

?

Is there any format recommendation for 3390-3 or 9 or 27?

Is there performance gain copying to another format?

?

De: [email protected] <[email protected]> Em nome de Rahim Azizarab via groups.io
Enviada em: segunda-feira, 29 de abril de 2024 20:01
Para: [email protected]
Assunto: Re: [H390-MVS] CKD, CCKD and CCKD64 devices

?

CCKD64 for some reason does not like to get tared and bzip2ed subsequently I can't make a reliable backup tar ball of the system when using CCKD64.? The problem did not exist with the plain cckd dasd image.

?


regards;

Rahim??

?


??

?

?

On Monday, April 29, 2024 at 02:26:20 PM CDT, Jo?o Reginato <jb.reginato@...> wrote:

?

?

Hi everybody

?

What are the real differences between these file formats?

CKD, CCKD and CCKD64

TIA

Jo?o

?

?

?

?


--
att.
Jo?o


--
att.
Jo?o
 

开云体育

This might be a problem with bzip.

Tar and bzip are theoretically compressing and decompressing the same bytestream…

You might try using variations with cpio and other compression tools…


On Apr 29, 2024, at 6:00?PM, Rahim Azizarab via groups.io <rahimazizarab@...> wrote:

?
CCKD64 for some reason does not like to get tared and bzip2ed subsequently I can't make a reliable backup tar ball of the system when using CCKD64.? The problem did not exist with the plain cckd dasd image.


regards;

Rahim??



??



On Monday, April 29, 2024 at 02:26:20 PM CDT, Jo?o Reginato <jb.reginato@...> wrote:


Hi everybody

?

What are the real differences between these file formats?

CKD, CCKD and CCKD64

TIA

Jo?o

?

?

?

?


--
att.
Jo?o

 

Rahim Azizarab wrote:

CCKD64 for some reason does not like to get tared and bzip2ed
subsequently I can't make a reliable backup tar ball of the
system when using CCKD64. The problem did not exist with the
plain cckd dasd image.
Sounds like a bug in bzip2 and/or tar to me. In any case, you can be certain it has absolutely nothing to do with Hercules. AFAIK tar and/or bzip2 doesn't give a rat's ass WHAT the data looks like in a given file. It can be random garbage for all it cares.

Are you perhaps doing something stupid like trying to do your tar and/or bzip while Hercules (or some other process) still has the image open? What's the error you're getting? Show us evidence of your claim.

--
"Fish" (David B. Trout)
Software Development Laboratories

mail: fish@...
 

Jo?o Reginato wrote:

[...]
Is there any format recommendation for 3390-3 or 9 or 27?
And dasd device type whose architected capacity is 4GB or more should use either the CKD or CCKD64 formats. CKD if you don't mind having very large files consuming gobs of host disk space, or CCKD64 if you prefer using the least amount of host disk space.

For device types whose architected capacity is less than 4GB, use either CKD, CCKD or CCKD64 (i.e. any of the available formats you want).

For a list of IBM dasd device types and their architected capacities, please see:

*


(or HercGUI's "Help --> Dasd Geometry Chart" command.)


Is there performance gain copying to another format?
Possibly. Possibly not. Some argue that using plain CKD format is more efficient (even though it consumes more host disk space) since no CPU cycles are involved with compressing or decompressing the data, but others (such as me) feel using compressed CKD (e.g. CCKD64) is more efficient (as long as you have enough spare host CPU capacity of course) since less I/O if being transferred per read/write, not to mention less host file system cache space as well.

Which is best can only be semi-accurately determined by running your own benchmarks for yourself to see which is "faster" and/or "more efficient" for you, according to your own needs and data access pattern.

--
"Fish" (David B. Trout)
Software Development Laboratories

mail: fish@...
 

Nothing stupid; tar -cjvf is the command used; and Hercules was not active when doing the tar command.? It creates the tar ball; but the tar ball is useless on cckd64 files.


regards;

Rahim???



??



On Monday, April 29, 2024 at 08:43:53 PM CDT, Fish Fish <david.b.trout@...> wrote:


Rahim Azizarab wrote:

> CCKD64 for some reason does not like to get tared and bzip2ed
> subsequently I can't make a reliable backup tar ball of the
> system when using CCKD64. The problem did not exist with the
> plain cckd dasd image.

Sounds like a bug in bzip2 and/or tar to me. In any case, you can be certain it has absolutely nothing to do with Hercules. AFAIK tar and/or bzip2 doesn't give a rat's ass WHAT the data looks like in a given file. It can be random garbage for all it cares.

Are you perhaps doing something stupid like trying to do your tar and/or bzip while Hercules (or some other process) still has the image open? What's the error you're getting? Show us evidence of your claim.

--
"Fish" (David B. Trout)
Software Development Laboratories

mail: fish@...
 

On Tue, 30 Apr 2024 09:41:02 +0000 (UTC), "Rahim Azizarab via
groups.io" <rahimazizarab@...> wrote:

Hi Rahim. sorry to but in, it is ust curiosity.

Nothing stupid; tar -cjvf is the command used; and Hercules was not
active when doing the tar command.? It creates the tar ball; but the
tar ball is useless on cckd64 files.
Being cckd64 already compressed, whatever the algorithm used, the
compression part (-j in this case) of the tar process should not
increase the compression ratio. The tar file size can even be greater
than the sum of the tarred files sizes. It is absolutely expected.
That is why I hardly use compression to produce tar files from already
compressed files.

The way you describe the problem it sounds like the use of
compression of the tar of the cckd64 files cause some sort of
corruption of the contents. Are you talking about file corruption,
inefficiency in compression or both?


Regards



regards;

Rahim???



??



On Monday, April 29, 2024 at 08:43:53 PM CDT, Fish Fish
<david.b.trout@...> wrote:
Rahim Azizarab wrote:

CCKD64 for some reason does not like to get tared and bzip2ed
subsequently I can't make a reliable backup tar ball of the
system when using CCKD64. The problem did not exist with the
plain cckd dasd image.
Sounds like a bug in bzip2 and/or tar to me. In any case, you can be
certain it has absolutely nothing to do with Hercules. AFAIK tar
and/or bzip2 doesn't give a rat's ass WHAT the data looks like in a
given file. It can be random garbage for all it cares.

Are you perhaps doing something stupid like trying to do your tar
and/or bzip while Hercules (or some other process) still has the
image open? What's the error you're getting? Show us evidence of your
claim.






Roxo

--
---------------- Non luctari, ludare -------------------+ WYSIWYG
Fernando M. Roxo da Motta <mvs@...> | Editor?
Except where explicitly stated I speak on my own behalf.| VI !!
PU5RXO | PX5Q6048 | I see text,
------------ Quis custodiet ipsos custodes?-------------+ I get text!
 

Ok, thank you for the complete explanation

-----Mensagem original-----
De: [email protected] <[email protected]> Em nome de Fish Fish via groups.io
Enviada em: segunda-feira, 29 de abril de 2024 23:00
Para: [email protected]
Assunto: Re: [H390-MVS] CKD, CCKD and CCKD64 devices

Jo?o Reginato wrote:

[...]
Is there any format recommendation for 3390-3 or 9 or 27?
And dasd device type whose architected capacity is 4GB or more should use either the CKD or CCKD64 formats. CKD if you don't mind having very large files consuming gobs of host disk space, or CCKD64 if you prefer using the least amount of host disk space.

For device types whose architected capacity is less than 4GB, use either CKD, CCKD or CCKD64 (i.e. any of the available formats you want).

For a list of IBM dasd device types and their architected capacities, please see:

*


(or HercGUI's "Help --> Dasd Geometry Chart" command.)


Is there performance gain copying to another format?
Possibly. Possibly not. Some argue that using plain CKD format is more efficient (even though it consumes more host disk space) since no CPU cycles are involved with compressing or decompressing the data, but others (such as me) feel using compressed CKD (e.g. CCKD64) is more efficient (as long as you have enough spare host CPU capacity of course) since less I/O if being transferred per read/write, not to mention less host file system cache space as well.

Which is best can only be semi-accurately determined by running your own benchmarks for yourself to see which is "faster" and/or "more efficient" for you, according to your own needs and data access pattern.

--
"Fish" (David B. Trout)
Software Development Laboratories

mail: fish@...












--
att.
Jo?o
 

开云体育

What is the md5sum for the file before and after extraction with tar?

They should be the same.

The cmp command will tell you the first byte that’s different.



On Apr 30, 2024, at 4:41?AM, Rahim Azizarab via groups.io <rahimazizarab@...> wrote:

?
Nothing stupid; tar -cjvf is the command used; and Hercules was not active when doing the tar command.? It creates the tar ball; but the tar ball is useless on cckd64 files.


regards;

Rahim???



??



On Monday, April 29, 2024 at 08:43:53 PM CDT, Fish Fish <david.b.trout@...> wrote:


Rahim Azizarab wrote:

> CCKD64 for some reason does not like to get tared and bzip2ed
> subsequently I can't make a reliable backup tar ball of the
> system when using CCKD64. The problem did not exist with the
> plain cckd dasd image.

Sounds like a bug in bzip2 and/or tar to me. In any case, you can be certain it has absolutely nothing to do with Hercules. AFAIK tar and/or bzip2 doesn't give a rat's ass WHAT the data looks like in a given file. It can be random garbage for all it cares.

Are you perhaps doing something stupid like trying to do your tar and/or bzip while Hercules (or some other process) still has the image open? What's the error you're getting? Show us evidence of your claim.

--
"Fish" (David B. Trout)
Software Development Laboratories

mail: fish@...

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