Another point I¹ve not seen mentioned, and I¹m not sure if it¹s true or not...
Given a dedicated volume to a Linux guest, won¹t the guest start only one I/O to the device at a time, and wait for it to complete? If you break up a larger volume into several minidisks (like a mod 27 into mod 9¹s) aren¹t you allowing the z/VM multipathing to do its job more efficiently, even if you give all the smaller volumes to the same Linux guest? Like I said, I may be totally off base, but this is the impression I¹ve had... -- Robert P. Nix Mayo Foundation .~. RO-OE-5-55 200 First Street SW /V\ 507-284-0844 Rochester, MN 55905 /( )\ ----- ^^-^^ "In theory, theory and practice are the same, but in practice, theory and practice are different." On 3/24/10 2:38 PM, "Scott Rohling" <scott.rohl...@gmail.com> wrote: > 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. > > On Wed, Mar 24, 2010 at 11:53 AM, Martin, Terry R. (CMS/CTR) (CTR) > <terry.mar...@cms.hhs.gov> wrote: >> 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 >> >> > >
