2GB is the maximum you can put in a single dataspace. And no, it does not all have to reside in main memory at the same time. It is paged just like any other dataspace (VM).
When a dataspace enabled directory is first accessed, a dataspace is created and the directory loaded into it. That can cause a noticeable delay for the first access. Subsequent accesses are made to the dataspace created by that first access and are nearly instantaneous. When the last accessor releases the dataspace, it ceases to exist. Regards, Richard Schuh -----Original Message----- From: The IBM z/VM Operating System [mailto:[EMAIL PROTECTED] On Behalf Of Michael Coffin Sent: Monday, July 16, 2007 8:06 AM To: [email protected] Subject: Re: Shared File Systems and Dataspaces Hi DK, Wow, so if I have a DIRCONTROL directory with 100Gb of data, I'd need to have enough storage (main, expanded and paging) for the ENTIRE 100Gb + FSTs? Darn, I can't see how Dataspaces could be effectively used except in situations where you have very small directories/contents and/or very large total storage. I do see the advantage of the XC machines "sharing" the contents, and in using the paging I/O routines - but the OVERALL price would just be too high for what I had intended it for. Maybe I can do this for just a few smaller but often referenced directories. Michael Coffin, President MC Consulting Company, Inc. 57 Tamarack Drive Stoughton, Massachusetts 02072 Voice: (781) 344-9837 FAX: (781) 344-7683 [EMAIL PROTECTED] www.mccci.com -----Original Message----- From: The IBM z/VM Operating System [mailto:[EMAIL PROTECTED] On Behalf Of David Kreuter Sent: Monday, July 16, 2007 10:56 AM To: [email protected] Subject: Re: Shared File Systems and Dataspaces 1. FSTs and file data 2. Storage is taken from main storage, and paging space as required by CP. So it could be in expanded storage or disk, and then pulled into main when needed. This is a good thing as the I/O is handled by CP with the goodness of the paging i/o routines. 3. The client virtual machine when in XC mode can directly reference the contents of a dircontrol DS directory. 4. A dataspace is technically just another address space; just like your virtual machine memory is an address space albeit one that you can execute instructions from. A dataspace cannot be used to execute instructions, but can hold lotsa data. David Kreuter -----Original Message----- From: The IBM z/VM Operating System on behalf of Michael Coffin Sent: Mon 7/16/2007 10:46 AM To: [email protected] Subject: [IBMVM] Shared File Systems and Dataspaces Hi Folks, I have a question about SFS use of Dataspaces. When you designate a DIRCONTROL directory to use Dataspaces, what exactly gets placed in the DS storage, and where does the DS storage get taken from? Does DS storage get taken from available DPA or expanded storage for exclusive use as DS storage, and attached to the SFS server in some fashion? In terms of what gets placed in that storage, is it just the FST's to speed up access to the file contents, or is it the ENTIRE contents of each file requested? I'm trying to do some sizing for some of our SFS servers, but having difficulty understanding exactly WHAT will be placed in the DS's, and where that storage will be taken from. -TIA Michael Coffin, President MC Consulting Company, Inc. 57 Tamarack Drive Stoughton, Massachusetts 02072 Voice: (781) 344-9837 FAX: (781) 344-7683 [EMAIL PROTECTED] www.mccci.com <http://www.mccci.com/> <http://www.spamabuse.org/images/anti-spam.gif>
