Re: Linux file system cache
On Fri, 12 Feb 2010 16:56:48 +1000 Shane wrote: > For those interested, here is the discussion on lkml; > http://lkml.org/lkml/2007/1/23/263 > > It's not like it was rejected without any consideration. > In the time I have been (occasionally) lurking lkml, this has been > raised more than once - and got nowhere. > Maybe Alan Cox will offer a comment. The kernel takes the view that free memory is waste memory. The page cache therefore isn't turned into free space as pages are not needed but instead the vm makes sure most of it is 'clean' - ie correct on disk. That means that when pages are needed the vm simply tosses stuff out of the page cache. If you suddenely need a lot of memory then all the unused bits in the page cache get tossed. When measuring it also remember that a lot of stuff in the page cache will be things like undirtied pages of executables you are running, mapped files etc - it's not a simple buffering system for disk writes. Virtualisers normally interact with all this by having drivers in each guest that allocate memory in respose to global hypervisor managed demand and peeking at local behaviour. The allocated pages are then removed from the guest and given by the hypervisor to another guest and vice versa as demand shifts. Effectively the total pages available is rather lower than the guests perceive. Alan -- For LINUX-390 subscribe / signoff / archive access instructions, send email to lists...@vm.marist.edu with the message: INFO LINUX-390 or visit http://www.marist.edu/htbin/wlvindex?LINUX-390
New Virtualization Cookbook for z/VM 6.1 and SLES 11
Hello lists (cross posted to linux-390 and ibmvm), Marian Gasparovic and I are pleased to announce a new "cookbook" entitled "z/VM and Linux on IBM System z: The Virtualization Cookbook for SLES 11". It is temporarily at the top of the page: http://www.vm.ibm.com/devpages/mikemac/ The PDF weighs in at 4.5MB and 236 pages. The associated tar file is only 17KB. There was no funding/support for this to become an official IBM Redbook, so we updated it "on the side". It is currently on my z/VM developer page, but we hope to finalize it on linuxvm.org/present (if Mark ever finishes his promised review :)) The changes to this book are: -) The z/VM sections are updated for V6.1 -) The Linux sections are updated for SLES 11. -) The REXX EXEC and XEDIT macro to help modify z/VM system labels have been removed as it is recommended to change the system labels at z/VM install time. For reference, the section on relabeling system volumes is slightly modified to describe performing the steps manually, without the REXX EXEC and XEDIT macro. -) The "Servicing z/VM" chapter has been updated for z/VM 6.1 and now describes IBM ShopzSeries, not IBMLink. -) The Linux system that does the cloning is called the cloner, not the controller. -) A section on the X Window System has been added. -) The penguin on the cover representing the golden image was given a gold jacket :)) Some sections are removed in the release of this book: -) In Miscellaneous Recipes chapter, sections on LDAP, NTP, rsync and CMM were removed in the interests of time. -) Details on creating a travelling /home/ have been removed, however, a section with words of wisdom, based on a linux-390 append by Patrick Spinler, has been added. Thanks to all who helped to make this project possible (see list in Preface). Feedback is welcome on or off-list. Enjoy - you can't beat the price! :)) "Mike MacIsaac"(845) 433-7061 -- For LINUX-390 subscribe / signoff / archive access instructions, send email to lists...@vm.marist.edu with the message: INFO LINUX-390 or visit http://www.marist.edu/htbin/wlvindex?LINUX-390
Re: New Virtualization Cookbook for z/VM 6.1 and SLES 11
Mike, Will you be coming out with a Red Hat version of this same cookbook (RHEL 5.4 & zVM 6.4)? James Chaplin Systems Programmer, MVS, zVM & zLinux Base Technologies, Inc -Original Message- From: Linux on 390 Port [mailto:linux-...@vm.marist.edu] On Behalf Of Michael MacIsaac Sent: Friday, February 12, 2010 8:34 AM To: LINUX-390@VM.MARIST.EDU Subject: New Virtualization Cookbook for z/VM 6.1 and SLES 11 Hello lists (cross posted to linux-390 and ibmvm), Marian Gasparovic and I are pleased to announce a new "cookbook" entitled "z/VM and Linux on IBM System z: The Virtualization Cookbook for SLES 11". It is temporarily at the top of the page: http://www.vm.ibm.com/devpages/mikemac/ The PDF weighs in at 4.5MB and 236 pages. The associated tar file is only 17KB. There was no funding/support for this to become an official IBM Redbook, so we updated it "on the side". It is currently on my z/VM developer page, but we hope to finalize it on linuxvm.org/present (if Mark ever finishes his promised review :)) The changes to this book are: -) The z/VM sections are updated for V6.1 -) The Linux sections are updated for SLES 11. -) The REXX EXEC and XEDIT macro to help modify z/VM system labels have been removed as it is recommended to change the system labels at z/VM install time. For reference, the section on relabeling system volumes is slightly modified to describe performing the steps manually, without the REXX EXEC and XEDIT macro. -) The "Servicing z/VM" chapter has been updated for z/VM 6.1 and now describes IBM ShopzSeries, not IBMLink. -) The Linux system that does the cloning is called the cloner, not the controller. -) A section on the X Window System has been added. -) The penguin on the cover representing the golden image was given a gold jacket :)) Some sections are removed in the release of this book: -) In Miscellaneous Recipes chapter, sections on LDAP, NTP, rsync and CMM were removed in the interests of time. -) Details on creating a travelling /home/ have been removed, however, a section with words of wisdom, based on a linux-390 append by Patrick Spinler, has been added. Thanks to all who helped to make this project possible (see list in Preface). Feedback is welcome on or off-list. Enjoy - you can't beat the price! :)) "Mike MacIsaac"(845) 433-7061 -- For LINUX-390 subscribe / signoff / archive access instructions, send email to lists...@vm.marist.edu with the message: INFO LINUX-390 or visit http://www.marist.edu/htbin/wlvindex?LINUX-390 -- For LINUX-390 subscribe / signoff / archive access instructions, send email to lists...@vm.marist.edu with the message: INFO LINUX-390 or visit http://www.marist.edu/htbin/wlvindex?LINUX-390
Re: New Virtualization Cookbook for z/VM 6.1 and SLES 11
James, > Will you be coming out with a Red Hat version of this same cookbook No, sorry, there are no plans for one at this time. "Mike MacIsaac"(845) 433-7061 -- For LINUX-390 subscribe / signoff / archive access instructions, send email to lists...@vm.marist.edu with the message: INFO LINUX-390 or visit http://www.marist.edu/htbin/wlvindex?LINUX-390
Re: zipl, bootmenu and FCP devices
> Am I reading that right? "Only for DASD disk devices"?Does this > mean that I have no alternative and no means to build a boot menu? Unfortunately this seems to be a feature of the scsi load mechanism. The boot configuration sections are still there, but it never puts up an actual menu to allow for dynamic selection. A target boot configuration can still be selected via the cp "set loaddev" command, ex: set loaddev bootprog 2 ipl a100 But the user has to know ahead of time which configuration matches which bootprog number. If it helps any, it is possible to write a rexx script based on the boot menu that you put in zipl.conf to query user input. Then have it run the loaddev bootprog command to set the correct number before doing the ipl. For an LPAR scsi load the bootprog number corresponds to the "Boot program selector" entry field. - Mark Ver office: Building 710 / Room 2-RF-10 phone: (845) 435-7794 [tie 8 295-7794] -- For LINUX-390 subscribe / signoff / archive access instructions, send email to lists...@vm.marist.edu with the message: INFO LINUX-390 or visit http://www.marist.edu/htbin/wlvindex?LINUX-390
