VDISK is a very good thing. Here's what we do for all of our servers...
In the VM Directory entry: *** vdisk for swap space - sizes can be changed if needed *** first disk has higher priority and will be used first MDISK FF00 FB-512 V-DISK 500000 MR MDISK FF01 FB-512 V-DISK 1000000 MR Then in the /etc/init.d/boot.local file /sbin/mkswap /dev/dasd/ff00/part1 /sbin/mkswap /dev/dasd/ff01/part1 /sbin/swapon /dev/dasd/ff00/part1 -p 2 /sbin/swapon /dev/dasd/ff01/part1 -p 1 We haven't investigated shared kernel - I don't think the effort is worth the benefits. But the perf experts can comment on that. Marcy Cortes "This message may contain confidential and/or privileged information. If you are not the addressee or authorized to receive this for the addressee, you must not use, copy, disclose, or take any action based on this message or any information herein. If you have received this message in error, please advise the sender immediately by reply e-mail and delete this message. Thank you for your cooperation." -----Original Message----- From: Linux on 390 Port [mailto:[EMAIL PROTECTED] On Behalf Of Dave Hansen Sent: Thursday, February 22, 2007 11:23 AM To: LINUX-390@VM.MARIST.EDU Subject: [LINUX-390] Perceptions of zLinux Hello Group, We are looking at possibly reducing our memory usage and making our SLES9 z/Linux "better". There are different opinions about what to do and what the costs are. A). VM Memory Disk (VDISK). Currently we do not use VDISK for our production zLinux servers on our z/VM 5.2 system. I see SLES 10 recommends two VDISKs. Is there a downside to using VDISK? About the only thing I saw is that VDISK doesn't do expansion or contraction, so you may need to "monitor" its usage. The popular thing I can see is to VDISK the swap filesystem, which we don't do. It sounds to me that even if you only have one zLinux you want to use VDISK (at least for swap). B). Shared Kernel. This is an NSS and not just a DCSS for the filesystems like "/var" (I think "/" or root is not supported in a DCSS anymore). So this is what I IPL. If it's not there, I can't IPL. We have been kicking this idea around for a while. But with only a dozen penguins of different configurations (WebShere or not, monitors etc.), I'm not sure we would gain much. Again I looked at what it costs. I found this in the IBM literature: "Every virtual machine that IPLs your shared system must have the same disk configuration as the system that was saved. That is, the disks must be at the same addresses and be the same sizes as the virtual machine that issued the SAVESYS command". What this means to me is we need every zLinux that IPLs the NSS has to have the same filesystems (in size and number). Furthermore I found that previously it looks like LKCD (Suse Crash Dump) didn't work well when you IPLd an NSS. All I can find now is that there appears to be a new LKCD2. I also found LKDTT, but it requires a kernel patch and a kernel re-compile. I thought re-compile = unsupported (tainted) zLinux? So then who would want your dump? Do we need to re-compile the kernel for "crash dump" support? Does it matter if we IPLd from an NSS? Are there any kernel parameters related to using an NSS? I saw a post from this year that talks about "Boot from NSS support" and a parameter "SAVESYS=". If we go through with this for only a few penguins is this worth it (besides having a good procedure to grow the farm)? Thank you, Dave H. ---------------------------------------------------------------------- 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 ---------------------------------------------------------------------- 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
