The chmount command can change a file system from Read Only to Read/Write and back.
-----Original Message----- From: IBM Mainframe Discussion List <[email protected]> On Behalf Of Israel Wagshal Sent: Sunday, July 12, 2020 11:50 AM To: [email protected] Subject: Re: Is /usr/lpp reserved solely for IBM products? On Sat, 11 Jul 2020 17:09:32 -0500, Al Ferguson <[email protected]> wrote: Thank you for the insights. How do you change dynamically root filesystem's mount mode to R/W and back to R/O? What do you mean by saying "the IBM Root Filesystem is actually mount at /ipl-vol/ "? The Version root has to be mounted R/O off a mountpoint at the Sysplex root. We do not place any VSAM dataset on the iplvol. Only non-VSAMs are placed there, because we use symbolic cataloging via &SYSRS1 and &SYSRS2, which isn't possible (I think) for VSAM datasets. >Isreal, > > >> On 11 July 2020, at 15:30, Paul Gilmartin >> <[email protected]> wrote: >> >> On Sat, 11 Jul 2020 12:51:04 -0500, Israel Wagshal wrote: >>> >>> I'm installing a software that has to have its own zFS aggregate mounted >>> and available. >>> >>> Looking into the USS filesystem I can see many IBM products' zFS aggregates >>> mounted off /usr/lpp. >>> I can see no foreign aggregate mounted off /usr/lpp. >>> >> I believe LPP abbreviated Licensed Program Products. > > >That is what IBM has designated it. IBM though does not say it is for IBM >Licensed Program Products. CA (now Broadcom) uses /usr/lpp/CA/product_name >quit a bit; as do a few others. > > >> The convention elsewhere seems to be /usr/local: >> >> https://www.pathname.com/fhs/pub/fhs-2.3.html#USRLOCALLOCALHIERARCHY > >The common place to put most Open Source tools is /usr/local/tool_name; >particularly in Linux installations. Occasionally some 3rd Party Products use >this as well (though they also end up in /var and /opt quite a bit). > > >>> However, /usr/lpp is in IBM's Version root which is mounted R/O. > >This is recommended configuration > > >>> >>> Is it proper to change Version root's mount mode temporarily to R/W and >>> mkdir another mountpoint off /usr/lpp for the product I'm installing, or >>> should this be avoided and made elsewhere? >>> Is there a general recommendation where to mount aggregates for non-IBM >>> products? >>> The vendor says nothing about this. >>> >>> Can mount mode of the Version root be changed on the fly by some command or >>> will this require bouncing the system? > >You can dynamically change the IBM Root Filesystem (or any mounted Filesystem) >from r/o to r/w and back again (line commands or via ISHELL Filesystem >utility), you do need to be root (either via “su” command or your UID being 0). > >What I have found to do to try to align with IBM’s intentions is the following: > >1. Create a mount point in the root filesystem to mount 3rd party products, >say /products. >I use a Automount to dynamically mount filesystems here. With proper naming >standards you can code a general rule in the /etc/automount/product config >file (or just hard code then as needed and refresh vial the automount command). > >2. Copy the 3rd Party Product to a Filesystem of its own. >If the vendor, say CA, suggests /usr/lpp/CA/caldap/...; I install it at the >/caldap/… level at the Filesystem. > >3. Mount the filesystem so it is available, say the Filesystem is mounted at >/products/CALDAP … the product directory would be at /products/CALDAP/caldap. > >4. Dynamically change root filesystem to r/w > >5. Create a Soft Link in the /usr/lpp directory (e.g. “ln -sf >/products/CALDAP/caldap /usr/lpp/CA/caldap”) > >6. Verify it is available via “ls -alF /usr/lpp/CA/caldap” > >7. Dynamically change root filesystem back to r/o > >I prefer to do it this way for a couple of reasons: > > 1. Under Unix (USS is Posix 3 Unix) this wil behave exactly like it > was mounted at /usr/lpp/CA/caldap 2. I want to keep the IBM root > Filesystem as close to what is coming out of SMP/E as possible 3. I > do not want to mount Filesystems on the IBM Root Filesystem, if possible* 4. > May products (I have seen this with IBM, CA, Rocket, …) have configuration > files that point to their “suggested” mount point and these are not alway > documented and/or auto configured correctly. > 5. It is always easier talking with a vendors support is everything looks to > be configured as closely to the manual as possible. > >* I run in a Sysplex, with a share Sysplex Root Filesystem and the IBM >Root Filesystem is actually mount at /ipl-vol/ > > >_______________ > >Al Ferguson | mailto:[email protected] >Milwaukee, WI USA | http://www.neptunescove.org > >Dulcius ex Asperis > > > > >---------------------------------------------------------------------- >For IBM-MAIN subscribe / signoff / archive access instructions, send >email to [email protected] with the message: INFO IBM-MAIN ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN Email secured by Check Point ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
