What is difference between installing Java in HFS or zFS

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demecarv
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What is difference between installing Java in HFS or zFS

Post by demecarv » Sat Feb 27, 2016 7:27 am

The context: I am installing for the first time Java in mainframe Z/OS 390. I am about to follow the procedures found in "SDK8_64bit_readme.txt". There is certain step which states:

(4) Create an HFS or zFS filesystem dataset into which you'll later expand
the pax file. Mount this filesystem at: /usr/lpp/java/Jv.r{_64}

Sorry for analogy with Windows but I am really new on mainframe: in Windows we never ask ourself which filesystem to use, I mean it wouldn't make sense to think "should I use FAT32 or NTFS". It wouldn't make sense since the entire drive is only one type. If I understood correctly, I am choosing between two types of filesystem, HFS or zFS. So my dummy question is: should I be aware about any possible difference if I choose HFS or zFS? When I open "Command Prompt" via OMVS or iShell command, browse to certain folder, and type mkdir, am I creating a HFS or zFS folder?



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Robert Sample
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Re: What is difference between installing Java in HFS or zFS

Post by Robert Sample » Sat Feb 27, 2016 8:54 am

When I open "Command Prompt" via OMVS or iShell command, browse to certain folder, and type mkdir, am I creating a HFS or zFS folder?
Yes. Depending upon how your site is set up, when you create a directory (Unix does NOT have "folders" -- that is a Windows term and it is incorrect to apply it to Unix or z/OS), the directory may be created on an HFS or zFS file system. HFS is older and functionally stabilized (IBM-talk for it's going away eventually), but is still quite commonly used. zFS is newer and being updated with every release of z/OS. HFS is a sequential data set while zFS uses VSAM Linear data sets.

The only time you will be concerned about whether or not HFS or zFS is the choice is when you mount a file system (either using the mount OMVS command or by using the ishell menu), when you have to tell Unix System Services whether the file system is HFS or zFS. Creating a directory is NOT going to create a file system -- only the mount operation brings one into use. They are created by JCL (for HFS) or IDCAMS / OMVS (for zFS).

While this is not done on Windows machines, it is not at all unusual for a Unix or Linux user to mount or unmount file systems and frequently they have the choice of which type of file system to mount (not zFS / HFS, but others). When you mount a Windows network drive, you don't generally have to tell Windows which type of file system it is, but that's Windows. You may be an expert on Windows use, but Unix / Linux / z/OS have their own way of doing things that is different from Windows. Not necessarily better, not necessarily worse, but definitely different and you'll have to get used to those differences.



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BobThomas
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Re: What is difference between installing Java in HFS or zFS

Post by BobThomas » Wed Mar 02, 2016 12:33 pm

Read through this article from Jim Showalter on Differences between HFS and zFS and you might better understand the difference between the two:
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