I second (or third) the motion to consider VDISK. \ For years I was worried that it would swamp our limited real storage (1G). But in real-life experience it has been FANTASTIC! Even with two 3390-3s reserved for TDISK, we used to frequently run into fragmentation. Formatting VDISK is instantaneous (regardless of size), and the I/O is awesome (no moving parts!).
We've had a local TDISK EXEC here since almost day one. It just took a small change, defaulting to VDISK (but allowed options to force it to be allocated on with VDISK or TDISK). Happier (much) users, no more fragmentation. Virtual life's great. Mike Walter Hewitt Associates The opinions expressed herein are mine alone, not my employer's. "Schuh, Richard" <[EMAIL PROTECTED]> Sent by: "VM/ESA and z/VM Discussions" <[email protected]> 01/24/2006 10:33 AM Please respond to "VM/ESA and z/VM Discussions" <[email protected]> To [email protected] cc Subject Re: Tdisk question Mary, If you have sufficient paging space, you might consider using V-disk instead of T-disk. As Nick pointed out, they are not subject to fragmentation and the limits for the individual users and the system as a whole can be set and adjusted dynamically. If you are not already paging constrained and you have the space, it might be a way out of the fragmentation problem. Look under HELP CP DEFINE (RELATED and select VDISK. You may also need to set limits using SET VDISK. We have been using V-disk in place of T-disk for the past several years and have never had a problem with it. -----Original Message----- From: VM/ESA and z/VM Discussions [mailto:[EMAIL PROTECTED] On Behalf Of Mary Zervos Sent: Tuesday, January 24, 2006 6:43 AM To: [email protected] Subject: Re: Tdisk question Thanks Jim for the insight. I had forgotten about fragmentation. Mary Jim Bohnsack wrote: > Mary--What you're seeing is fragmentation. TDISK is allocated in one > whole piece to a user. Think of PC disk allocation that you see when > you run a defrag. If you have 1 allocated cylinder out in the middle > of an otherwise empty 100 cylinder TDISK space, you cannot allocate a > 99 cyl TDISK. You would get that by the first user getting 50 > cylinders and the 2nd user getting 1 cylinder. When the first user > detaches the 50 cyl. disk, the 2nd user still has the 1 cyl in the > middle. You are left with 99 cylnders in total free but you can only > allocate a max of 50 cylinders and 49 cylinders. > > Jim > > At 09:17 AM 1/24/2006, you wrote: > >> I have 500 cyl. of tdisk defined on one pack and 50 cyl. of tdisk >> defined on another. One user used the 50 cyl. on the second pack >> and about 24 users have used 215 cyl.(43%used) on the first pack. >> Why is it that I can only allocate a 130 cyl. maximum tdisk on the >> first pack but can then go ahead and allocate a 110 cyl. tdisk, >> instead of being able to allocate *one* 240 cyl. tdisk? >> >> Thanks for any help. >> >> Mary Zervos >> VM Systems Programmer >> Binghamton University >> [EMAIL PROTECTED] > > > Jim Bohnsack > Cornell Univ. > (607) 255-1760 The information contained in this e-mail and any accompanying documents may contain information that is confidential or otherwise protected from disclosure. If you are not the intended recipient of this message, or if this message has been addressed to you in error, please immediately alert the sender by reply e-mail and then delete this message, including any attachments. Any dissemination, distribution or other use of the contents of this message by anyone other than the intended recipient is strictly prohibited.
