Some more pedantism: For both dasd and SCSI disks, booting a rescue system on the downed zLinux server makes repairing the file easier: the VM userid already has access to the disk in question, no need to LINK to or get the other userid zoned/masked to the downed server's LUN.
> -----Original Message----- > From: Linux on 390 Port [mailto:[email protected]] On Behalf Of > Dave Jones > Sent: Thursday, June 25, 2009 1:51 PM > To: [email protected] > Subject: Re: Mounting root fs of one instance to another instance to > make repairs > > Not to be too pedantic here, but the methods being offered on how to > access one zLinux's file system from another, to make repairs or > whatever, all assume that the Linux file systems are on 'old-style' > mainframe DASD, either ECKD (3390) or FBA (either 9336 or EDEV). If the > zLinux guest is installed such that all of it's file systems are stored > on FCP-attached (SCSI) disk, the the simple approach of ATTACH xxxx, > chccwdev, mount, etc. doesn't work. > > Yes, it is possible to have a zLinux guest access another guest's FCP > based disk files, but it's a bit more of a hassle....which is why I > always suggest that things like the "/", "/etc", "/usr", and "/boot" > all > be allocated on 3390 DASD devices. Leave the really big Linux file > systems (e.g., Oracle databases) to the FCP disk. > > Have a good one. > > Richard Troth wrote: > > Good question, Ron. > > This is a case where LVMing the root can lead to pain. > > If the root is not LVMed, then you can follow Bernie's recipe. Easy! > > Otherwise (with logical volumes) you might have multiple PVs to > attach > > ... and worse ... what if the volume groups collide? (same name - > you > > can work around that, but it's tricky) > > > > > > When Linux is virtualized, it makes a lot of sense to let the host > > handle volume manglement and not toss everything into LVM. (A mix is > > usually best, not all one or the other.) Certainly the sometime need > > of recovering your root FS makes the root a poor candidate for > logical > > vol. > > > > > > Gary, for servicing a system like what you're asking about, I > > recommend that you pre-assign a range of addresses, places where you > > can plug-in a disk on-the-fly. (This is the kind of thing to be done > > ahead of the crisis.) Newer releases make this less necessary from a > > technical standpoint, but it still helps tremendously if you can > > visualize where you're attaching disks. My usual habit of a 1b0-1bf > > range for the primary system disks leads then to a 2b0-2bf range for > > "service" or other things. That's just one idea. 01xx and 11xx > works > > too. > > > > > > -- R; <>< > > > > > > > > > > > > On Thu, Jun 25, 2009 at 09:49, Ron Foster at > > Baldor-IS<[email protected]> wrote: > >> Gary, > >> > >> I need a little more information on how your systems are set up. > >> > >> Are you using lvm for your operating system disk on instance a and > >> instance b? > >> > >> Ron > >> > >> Lee, Gary D. wrote: > >>> Under vm 5.3 both instances are suse sles10. > >>> > >>> Some one edited the /etc/inittab on instance A. > >>> > >>> How can we mount instance a's root fs to instance b so as to fix > the > >>> inittab? > >>> Or, is there a better way? > >>> > >>> Thanks for any help. > >>> > >>> > >>> Gary Lee > >>> Senior System Programmer > >>> Ball State University > >>> phone: 765-285-1310 > >>> > > -- > Dave Jones > V/Soft > www.vsoft-software.com > Houston, TX > 281.578.7544 > > ---------------------------------------------------------------------- > For LINUX-390 subscribe / signoff / archive access instructions, > send email to [email protected] with the message: INFO LINUX-390 > or visit > http://www.marist.edu/htbin/wlvindex?LINUX-390 This e-mail, including any attachments, may be confidential, privileged or otherwise legally protected. It is intended only for the addressee. If you received this e-mail in error or from someone who was not authorized to send it to you, do not disseminate, copy or otherwise use this e-mail or its attachments. Please notify the sender immediately by reply e-mail and delete the e-mail from your system. ---------------------------------------------------------------------- For LINUX-390 subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO LINUX-390 or visit http://www.marist.edu/htbin/wlvindex?LINUX-390
