Thanks all for the information.
As far as DEDICATING the volume is concerned I thought that the I/O overhead was cheaper that is why I was wondering about this. I am fine with doing the way I have always done it (MDISK) but someone had suggested this to me and I wanted to find out more about the pros and cons. In terms of the INIT I just thought since z/Linux was doing the Initialization at Kick Start time in my case that it did not make sense to init the DASD twice. I did not think about Cyl0. Thanks again for all the help as always it has been enlightening! Thank You, Terry Martin Lockheed Martin - Citic z/OS and z/VM Performance Tuning and Operating Systems Support Office - 443 348-2102 Cell - 443 632-4191 From: The IBM z/VM Operating System [mailto:[email protected]] On Behalf Of Scott Rohling Sent: Wednesday, March 24, 2010 3:39 PM To: [email protected] Subject: Re: initializing z/Linux disks Terry -- You have to init the DASD when using minidisks- using CPFMTXA to put a label on -- and you also want to format cylinder 0 to ensure it's seen as a CP volume. When the zLinux guest does an 'init' -- it is doing a format of the whole disk - not just an 'init' and label. You can preformat minidisks in Linux format if you want to avoid the time Linux takes to do it at kickstart... if that's what you're looking for. I would not recommend using DEDICATE -- why would you do that rather than use minidisks? What you need to be aware of is that if you DEDICATE -- Linux will label the DASD -- and that's what you'll see at the z/VM level -- and are likely to see duplicate labels. (to things like 0x0200 and 0x0300, etc...). Also - if you dedicate - you can't use things like DIRMAINT do manage your dasd and keep things in pools, etc -- you have to manage it all yourself. I'm not sure how DFDSS reacts to Linux formatted volumes, offhand .. it does fine with CPVOL volumes and minidisks. Anyway - I'm not a fan of dedicate's - as you can tell ;-) Scott Rohling On Wed, Mar 24, 2010 at 11:53 AM, Martin, Terry R. (CMS/CTR) (CTR) <[email protected]> wrote: Error! Filename not specified. Hi I have a question. What I have been doing up to this point for a new z/Linux guest build is, not necessarily in this order and does not necessarily include all steps but, Crave out the DASD for the z/Linux guest Init the DASD using CPFMTXA putting a label on the disk Setting up the Directory entry for the new guest, which includes specifying the MDISK for all of the DASD for the guest. We back up our z/Linux guests on the z/OS side with DFDSS. My question is since when we Kick Start the new z/Linux guest and it initializes the DASD during this process is there any compelling reason for me to initialize the DASD up front before the guest is Kick Started for the first time basically doing a double INIT? If not I assume then I would replace the MDISK statements in the Directory entry with DEDICATE statements for each one of the DISKS. We do not share DASD between guests here so what is defined to the guest belongs to that guest only. Is there anything to be aware of by changing to DEDICATE statements from MDISK statements? My only concern is with the DFDSS backups that I do on the z/OS for the guests. I am not sure if it matters or not to DFDSS whether the pack was initialized via CPFMTXA or z/Linux during the kick start process? Thank You, Terry Martin Lockheed Martin - Citic z/OS and z/VM Performance Tuning and Operating Systems Support Office - 443 348-2102 Cell - 443 632-4191 Error! Filename not specified.
