... Alternative Linux distributions for POWER processor-based systems A review of unsupported Linux distributions running on POWER5

Transcription

1 A review of unsupported Linux distributions running on POWER John Engel & Brent Baude IBM eserver Solutions Enablement January 2006 Copyright IBM Corporation, All Rights Reserved. All trademarks or registered trademarks mentioned herein are the property of their respective holders

2 Table of Contents Abstract... 4 Introduction... 4 Distribution test environments... 4 Standalone with a video card... 4 Standalone with a serial console... 5 Logical partition... 5 IBM-related software packages... 6 iprutils... 6 ppc64utils and librtas... 6 Dynamic LPAR tools... 7 opensuse Install experience... 7 Standalone with video Standalone with serial Logical partition Library support Package management Fedora Core Install experience Standalone with video Standalone with serial Logical partition Library support Package management Debian GNU/Linux Install experience

3 Standalone with video Standalone with serial Logical partition Library support Package management Gentoo Install experience Standalone with video Standalone with serial Logical partition Library support Package management POWER-ready Conclusions and summary Resources About the Authors Trademarks and special notices

4 Abstract Follow along as the authors review several alternative Linux distributions for the POWER5 platform. After discussing their test environment, they attempt to install Debian, Gentoo, opensuse 10, and Fedora Core 4 on an IBM eserver OpenPower 720 system in a variety of configurations. In each case, the authors summarize their install experience as well as document any issues they found. Introduction As of the writing of this document, Novell's SUSE Linux Enterprise Server Version 9 (SLES9) ( and Red Hat Enterprise Linux AS Versions 3 and 4 (RHEL 3 and 4) ( ) are the only Linux distributions for the POWER5 platform formally approved by IBM and the distributions themselves. Both are proven enterprise-ready Linux distributions in full production use on several different architectures. Most companies looking to sell their applications on the POWER platform target one of these two distributions. Therefore, most Linux users tend to go with these mainstream distributions because they provide the sort of function, reliability, and support need. However, a recent variant of distributions have cropped up that claim to work on POWER5 platforms. For lack of a better term, we will call these alternate Linux distributions. The purpose of this paper is to evaluate these alternate Linux distributions to see how advanced they are and get a better understanding of them. In this paper, we will review the latest version of OpenSuSE, Debian, Gentoo, and Fedora Core 4. In each review of the distribution, we have provided a small rating for the distribution based on our experiences with installing and using the distribution itself. These ratings are not related to each other, but rather our personal impressions and are not meant as an endorsement of any distribution over another. Some of these distributions are still works of progress; others are a bit more mature. And that is reflected in our experiences and ratings. Distribution test environments For test equipment, we used an eserver OpenPower way system with ample disk and memory. To test the readiness of each distribution for a POWER5 system, we determined there are three common configurations that it needs to support. The differentiating factor in configurations is the configuration and enablement of the console device. In the upcoming sections, we describe each configuration and what sort of details need to be accounted for either in the kernel or the installer. Standalone with a video card The term standalone refers to a server that has not been logically partitioning. It, therefore, requires no HMC or Integrated Virtualization Manager. A standalone system can also use a PCI video card and monitor for a console and USB keyboard and mouse for input. A Matrox video card is the most commonly used video card on a POWER5 processor-based system. In order for a distribution to successfully operate in this configuration, the kernel must have the proper Matrox kernel driver (and/or framebuffer) for the video to work properly. Also, the USB drivers must load for the input to work. 4

5 Standalone with a serial console This scenario is very similar to the previous configuration but instead of using a video card for a console and USB devices for input, you use a serial cable to connect another device like a laptop to the POWER5 server. Then you use a terminal emulation program like HyperTerm, minicom, or Kermit for console input and output. While serial console is commonly used tactic with Linux, the serial console function works a bit differently on the POWER5 platform. On the x86 platform, serial console devices are usually something like /dev/ttys0 for the first serial port. And when you want to use serial console, the boot loader will pass something like console=ttys0 as a kernel argument. On the POWER5 platform, however, the serial console device is actually /dev/hvsi0 for the first serial port. And therefore, console=hvsi0 must be passed to the kernel. Both the installer and post-install configuration should account for the user needing a serial console. This means the installer needs to be told the user is using a serial console or it should detect it automatically. In the post-install configuration, the installer should also have the appropriate serial-related entries in /etc/inittab and /etc/securetty. And if the distribution does not use udev, then MAKEDEV (or some manual process) must create a character device entry in /dev with major number of 226 and minor number starting at 128. Author's Note We have had mixed successes with passing and not passing the console=device arguments to kernel at boot time. In some cases, the lack of passing the console device resulted in kernel panics; while in other cases, it worked perfectly fine. As a general rule of thumb, however, we felt it was best to pass the console device in a serial console scenario and this is more in line with what an x86 architecture would also do. In /etc/inittab for serial console, there should be an entry similar to the following: hvsi:12345:respawn:/sbin/agetty -L hvsi0 This entry will allow init to spawn a console to the serial device and thus a login. That same hvsi0 device should also be in /etc/securetty. Only devices that are in securetty are allow to have root logins on them. Since the serial console is the primary console device, it makes good sense for the device to be there to allow root logins. Logical partition One of the attractive features of POWER5 processor-based servers is their ability to run Linux in logical partitions. For an overview of logical partitioning and Linux on POWER5, see the following reference: A partitioned system generally has a more dynamic set of possibilities in its device configuration. Like the two earlier configurations, the console output and input is a factor for logical partitioning. For console input and output on a Linux partition, the console device is typically /dev/hvc0. Like the serial console example above, the installer and post-install configuration need to account for this type of console access. Like the serial console example, this console needs to have an entry in /etc/inittab and if the distribution does not use udev, it must also create a character device entry in /dev/with major number of 226 and minor number starting at 0. Something like this is usually sufficient: 5

6 hvc0:1235:respawn:/sbin/agetty -L 9600 hvc0 And the hvc0 device must also be added to /etc/securetty to allow root logins on that console. With logical partitioning, there is also an increased likelihood for the use virtual disk and virtual Ethernet. Both of these functions are delivered through kernel modules, which should be be enabled on both the installer kernel and the post-install kernel. The modules are CONFIG_SCSI_IBMVSCSI and CONFIG_IBMVETH respectively. IBM-related software packages While the POWER5 server can run a multitude of Linux packages, there are a few packages that compliment the POWER5 server itself. While none are required per se, at least one can significantly impact performance and others provide very handy function. The following subsections describe these packages and their uses. iprutils The iprutils package is a set of utilities that configure and control the IPR-based SCSI and SCSI-RAID cards in POWER5 servers. The source code and binaries for iprutils can be found at Simply put, it has two broad functions. One is a utility called iprconfig, which allows you to interact with the SCSI cards, disks, and hardware RAID configuration. The second set of functions is delivered through init.d functions. These daemons monitor the SCSI cards and one of them actually enables the SCSI cards to achieve a possible 320 MB/sec throughput. Without these daemons, the throughput is significantly less. ppc64utils and librtas The ppc64utils and librtas packages allow for a Linux partition to participate in more Serviceability tasks. The main location for these utilities can be found at: The utilities in the ppc64-utils package enable a number of RAS (Reliability, Availability, and Serviceability) features. Among others, these utilities include : update_flash: a utility for installing system firmware updates serv_config a mechanism for modifying various serviceability policies usysident and usysattn: utilities for manipulating system LEDs bootlist: a utility for updating the list of devices from which the system will boot snap: a utility for capturing extended error data to aid analysis of intermittent errors. As for librtas, it contains a library that allows applications to access certain functionality provided by platform firmware. This functionality is required by many of the other higher-level service and productivity tools. 6

7 Dynamic LPAR tools Dynamic logical partitioning increases the flexibility of partitioned systems by enabling administrators to add, remove, or move system resources between partitions without the need to reboot the partition. To perform dynamic LPAR events, you must have a slew of applications. For an excellent resource on dynamic LPAR and the tools associated with performing dynamic LPAR tasks, see opensuse 10 In 2005, Novell made one of the biggest announcements in the Linux Quick Rating Guide community by opening up their SUSE Linux product to the community. POWER-ready The opensuse project offers an alternative solution to their enterprise Installer product SUSE Linux Enterprise Server (SLES) distribution. It differs Documentation from the SUSE Linux product by opening up its development and Package Availability testing to the open source community. There is a public bugzilla Specifications: database at where bugs can gcc be reported while source code is made available to the community for glibc those that want to contribute fixes and enhancements. The goal of kernel opensuse is to not only provide a distribution for experienced Linux users but also provide a choice for Linux enthusiasts of every skill level. According to the project roadmap at there will be one more alpha release followed by monthly beta releases leading up to a release candidate version of opensuse 10.1 in February of Install experience We used the alpha 3 release of opensuse 10 when testing on our POWER5 processor-based systems. The installs went smoothly with the exception of installing the yaboot boot-loader properly and a dependency issue with ppc64-utils. We just deselected ppc64-utils so it would not be installed. There is a work-around to overcome the boot-loader problem and once the boot-loader was installed, opensuse 10 ran fine on all three installation types. During our installs, we chose the network install option from the CD and performed an NFS install. The following list outlines the workaround necessary to get the bootloader installed: 7

8 1. Continue with the installation until you are at the Installation Settings screen as in Figure 1 Figure 1 opensuse Installation Settings 2. Verify that that a small PREP partition was created around 8 MB. 3. Select the Booting option to configure the boot-loader. 8

9 4. Select Do Not Install Any Boot Loader from the Boot Loader Settings screen as in Figure 2. Figure 2 opensuse Boot Loader Settings screen 5. Continue with the installation. 6. After the installer finishes and reboots, boot off of the CD again. 7. Select Boot from Installed System and boot into the partition that was just installed. 8. The installation will finish and provide a login prompt. 9. Login in as root. 10. Copy the yaboot binary to the PREP partition dd if=/usr/lib/lilo/chrp/yaboot.chrp of=/dev/sda1 11. Create an /etc/yaboot.conf file such as: partition = 3 timeout = 100 default = linux image = /boot/vmlinux label = linux append = "root=/dev/sda3 selinux=0 elevator=cfq" initrd = /boot/initrd 12. The system should now boot off the hard drive. 9

10 Standalone with video No problems except for getting X to start. Standalone with serial It was difficult to navigate through the console because of the fonts. An ssh or vnc can be used to avoid this problem. Logical partition No problems. Library support opensuse installs a 64-bit kernel and a 32-bit user-land by default. However, there are 64-bit versions of many of the packages which you can install as your situations might dictate. opensuse contains a biarch compiler that can compile 32-bit and 64-bit binaries with the proper development libraries installed. The POWER5 specific package ppc64-utils was also on the CD but it has a dependency on the librtas package, which was missing. Also, there was no iprutils package. Package management ment OpenSUSE uses Yast2 for its RPM-based package management system. Yast2 also has an Online Update function that updates your current system with bug fixes including security updates. Fedora Core 4 Fedora Core 4 is an open source community based project sponsored by Red Hat Linux. This project contains recent code releases and has a more rapid development pace than Red Hat Enterprise Linux, which allows Red Hat to base their enterprise solution off of the well tested Fedora project. With the release of FC4, there is support for POWER5 processor-based systems. Install experience When performing our installations, we ran into the following error: Error bad argument --virtpconsole: unknown option Quick Rating Guide POWER-ready Installer Documentation Package Availability Specifications: gcc glibc kernel We searched the FC4 bugzilla database at and quickly found that this was a known bug with a fix already available and documented in bugzilla entry For our installations, we created a boot CD from the iso image provided in the directory /images/pserries/ on the first FC4 install CD. We then performed a network installation from an NFS server. The following steps allowed us to get around the bug: 1. Create an Rhupdates directory parallel to our Fedora install tree 10

11 2. Place the fixed copy of anaconda (from the bugzilla entry) in the Rhupdates directory After these steps, we were able to install on all three methods. Standalone with video No problems except that we couldn't get X to work. Checking the kernel config file in /boot, it appeared that CONFIG_FB_MATROXwas not set. We did not try rebuilding the kernel with this set to see if we could resolve the X server issue. Standalone with serial No problems. Logical partition No problems. Library support FC4 also contains a 64-bit kernel with a 32-bit userland by default but also provides many of the packages in a 64-bit variant if needed. FC4 contains the POWER5 specific packages ppc64-utils and iprutils but there was no librtas package. A bi-arch compiler is also available on FC4 for creating 32-bit and 64-bit binaries. The Compatibility Arch Development Support packages are necessary for 64-bit binaries. Package management FC4 uses RPM for its packages and provides a few different tools for software package management such as yum, up2date, and system-config-packages. The system-config-packages tool can be used to install software from the current release while yum and up2date will keep your system updated with the latest bug fixes and security fixes. Debian GNU/Linux Debian GNU/Linux is a free Linux distribution supported entirely by the community. It is often referred to as Debian for short. Debian GNU/Linux consists of a Linux kernel with software from the GNU project. Debian consists of three releases; stable, unstable and testing. Using a daily built netinst image which can be found at we performed a network instalation. The support for 64-bit POWER based processors is fairly new to Debian but with a little work, we were able to get a system up and running. Quick Rating Guide POWER-ready Installer Documentation Package Availability Specifications: gcc glibc kernel Install experience We encountered four main problems when installing Debian on our POWER5 processor-based systems. The problems, which are listed below, are related to the ongoing development of the installer for Power. 11

12 1) Unable to create a PREP partition and install yaboot 2) Virtual console devices were not created for HVSI and HVC installs 3) The Virtual SCSI CD was not detected when using a virtual cdrom 4) 32-bit kernel was installed by default The Debian installer lets you execute a shell during the installation, which made it easy for us to work around these problems. The following steps were used to work-around each problem. Create PReP partition and installing yaboot boot loader 1. Install system as normal 2. Select Partition Disks 1. The installer doesn't create PReP partition so remove all partitions 2. Create a new 8MB partition setting as do not use with the Bootable flag set to on 3. Continue creating a root partition and a swap partition 4. When the 1 st stage installer is finished and it is on the Finish the installation option, execute a shell 5. Change the root directory into the new installed system: chroot /target 6. Use cfdisk to create a PReP partition (set TERM variable if cfdisk output is not clear) cfdisk /dev/sda change /dev/sda1 to Type 0x41 (PreP) Write the changes and Quit 7. Copy the yaboot binary to the PReP partition dd if=/usr/lib/yaboot/yaboot of=/dev/sda1 8. Create a yaboot.conf file similar to the following: partition=2 timeout=100 default=linux image=/boot/vmlinux label=linux append="root=/dev/sda2" initrd=/boot/initrd.img 9. Exit out of shell and select Finish Installation 10. The system will reboot and you should be able to boot the system from the hard disk 11. Continue on with 2 nd stage installer 12

13 Install 64-bit kernel instead of default 32-bit kernel 1. Select the expert64 install option when booting from the CD 2. During the install, you will be prompted to select which kernel to install, choose the 64-bit kernel such as: linux-image powerpc64 Standalone with video The X server was not able to start at a usable resolution. Standalone with serial The hvsi support had to be added. 1. After 2 nd stage installer has completed (Exit the base system configuration), execute a shell 2. Create a device entry for hvsi. mknod /dev/hvsi0 c Create an entry in /etc/inittab.real (this gets renamed to /etc/inittab after reboot) for your hvsi console: hvs0:23:respawn:/sbin/getty -L hvsi vt Create an entry in /etc/securetty for either hvsi or hvc: Logical partition echo hvsi0 >> /etc/securetab The hvc device support had to be added. This can be done as follows: 1. After 2 nd stage installer has completed (Exit the base system configuration), Execute a shell 2. Create a device entry for the hvc console: mknod /dev/hvc0 c Create an entry in /etc/inittab.real (this gets renamed to /etc/inittab after reboot) for your hvc console: hvc0:23:respawn:/sbin/getty -L hvc vt Create an entry in /etc/securetty for either hvsi or hvc echo hvc0 >> /etc/securetty 5. Reboot the system Note: If you are using a virtual cdrom, you must do the following to continue installing from the CDROM: 1. Execute a shell from within the installer 2. Run the command: modprobe ibmvscsic 3. Return back to installer and have it detect CDROM again 13

14 Library support The current testing release of Debian contains a 64-bit kernel with a 32-bit userland. Debian includes a bi-arch compiler and toolchain to generate both 32-bit and 64-bit binaries. Since the Debian port to 64-bit POWER is fairly new, there currently are not any packages for the POWER specific tools such as ppc64- utils. Package management Debian uses the dpkg tool to manage software packages on a system and the apt tool for installing packages and resolving dependency issues on a system. You can configure apt to pull sources from different software repositories allowing for the testing of different packages which is useful when developing and testing new software (such as POWER enabled packages). Gentoo Gentoo has a distribution that supports a wide variety of POWER processor-based servers including Apple products and IBM POWER servers such as the OpenPower servers. The homepage for Gentoo is Quick Rating Guide POWER-ready Installer Documentation Gentoo is a highly customizable and potentially optimized Linux Package Availability distribution where almost all packages are compiled by the user at Specifications: installation time. With the use of simple configuration files, users can gcc enable and disable build features that they prefer. Gentoo also has a glibc reputation as a bleeding edge distribution in that the packages that are kernel available to users are typically newer than those of other Linux distributions. In that same light, Gentoo is often seen as a Linux distribution for semi-experienced users. For Gentoo's own description of themselves, see their About Gentoo page at Gentoo is free, community-based Linux distribution. You can download their install CDs from the Gentoo site or any one of the public mirrors. Their latest supported release media can be found here: As of this writing, there are basically still two variants of Gentoo for PowerPC those that run a 32-bit kernel (i.e. Powerbooks, imacs) and those that run the 64-bit kernel (i.e. Apple G5's, POWER4, POWER5, and JS20 blades). Given that the OpenPower runs a 64-bit kernel, the rest of this section applies to the 64-bit kernel variant of Gentoo. Install experience The install experience for Gentoo went very smooth. We used the r1 release media. After you have the media, you simply need to use that media and then you can pull the necessary packages from Internet mirror sites. The install documentation is quite mature and, with the exception of some minors 14

15 bugs, is very accurate. The installation documentation is located at: The install CD accounted for each of the test scenarios and the documentation discusses how to edit inittab for the proper console entries. Both the hvc and hvsi devices were already in securetty and therefore required no user interaction. Each of the test scenarios were successful during install and post-install. To get the the different consoles to work properly, there are several different yaboot labels for the pseries kernels on the install media. If you select the right label for the respective console, it worked perfectly. Standalone with video This worked smoothly by booting the ibm-power5 yaboot label. Standalone with serial You must select the ibm-power-serial yaboot label for this environment. The documentation tells you how to add the appropriate console device. Logical partition When booting a logical partition, you should select the ibm-power5-hvc yaboot label. The documentation tells you how to add the appropriate console device. Library support A recent change in Gentoo for ppc64 now allows for you to run a 64-bit kernel with either a 32-bit or 64-bit userland. This is determined by selecting the right profile from portage when installing your system. Each has its advantages and those advantages are really applicable to each persons own environment. The 32-bit userland will, of course, run 32-bit binaries but it also contains the right toolchain components to create 64-bit kernels. The 64-bit userland is a full 64-bit userland in that its toolchains cannot create or run 32-bit executables. When a 32-bit executable is absolutely required, such as for yaboot, which can only be compiled as 32-bit, there are static packages available. An evolution of these two userlands is being termed multilib by the Gentoo developers. Multilib will eventually allow users to have both 32-bit and 64-bit applications running in the same userland. The user will then be able to determine which bitness they want for different applications. For example, you might want a 64-bit Apache server but run a 32-bit version of Samba. This function is still in development but some users are experimenting with it. Package management The Gentoo package management system is called Portage. An introduction to portage can be found on the Gentoo web site at: Probably the most significant difference between Gentoo and other distributions is that Gentoo encourages you to compile your own packages (in fact the number of binary packages included in the tree is VERY small). Portage makes this easy and provides additional control over how things should be built via some configuration files. The portage configuration files can accept complex compile flags or 15

16 simple things like Gentoo's USE flag system. Using this system a user can for example add 'USE=ldap' to one of these configuration files to tell the package management system to compile in optional ldap support into the packages it builds. The package management system resolves all the dependencies and does all the work. This function is advantageous in two ways: you have more control of what is put on your system and you have more control on how that application behaves. The first advantages can be crystallized in the following short example. When you install an rpm, which is a binary package, onto your system, like in the case of SLES, it is generally compiled to what SLES believes are common options. Often this is good enough, but sometimes you get things you do not want. For example, if I want to install a program, which may or may not make use of ldap, the rpm will usually assume you want ldap; it will then install all the ldap rpms as dependencies, and then all of the dependencies for ldap, and so on. Gentoo's package management system allows you to turn a flag like ldap on or off, and based on the flag, will resolve (or not) the dependencies. This means you get your applications how you want them. The second advantage can be clarified with the following example. Let's assume you want to put Gentoo on a POWER5 system. Gentoo contains a power5 profile in its package management system, which describes how packages should be compiled for power5; specifically for power5, right down to the chip itself. This will allow applications that can take advantage of processor features to do so. The package management system is quite mature. Like rpm, it will allow you to install, uninstall, and do queries against packages. Portage also has the concept of stable and testing packages; both of which are in the portage tree. Stable means that the package has been tested and that both the Gentoo folks and the package owner agree, in principle, that the package is stable (the general rule of thumb is 30 days in the tree as a testing package with no outstanding bugs). Testing means that the application is either new to the architecture or is considered to be a new release that is not yet production-ready. POWER-ready Gentoo has packages for iprutils and for the ppc64utils and librtas. These packages are available on both the install media as well as post-installation. In fact, you can use the install media to configure RAID arrays and update the POWER5 firmware. However, at the time of this writing, Gentoo does not have a way to run the dynamic LPAR tools in their 64-bit userland. Conclusions and summary We believe that it is feasible to run any of the alternative Linux distributions on a POWER5 processorbased server with success. While each of the distributions had strengths and weaknesses, all of them showed promise, even in a production environment. Both opensuse and Gentoo, which seem to be a bit more mature than the other distributions we tested, could be used as infrastructure servers already based on our experiences with it. For example, DNS and DHCP servers or intranet web servers. While each of the distributions leaves room for improvement, we are seeing progress being made on each of them. Most of the problems we encountered were related to the installers not setting up something quite properly. The main culprits were the installation of the yaboot boot loader and the proper configuration of the serial (hvsi) and hvc console devices. And in the case where they did not work, we either contacted the distribution developers to communicate the problems or they were aware of them already and fixes were planned. 16

17 Resources The opensuse project is at Debian information can be found at Gentoo's home is located at The Fedora Project home is at opensuse PowerPC and POWER information can be found at Debian testing beta images can be found at Gentoo ppc64 specific information can be found at Information on Dynamic logical partitioning on for Linux on POWER can be found at ibm.com/developerworks/linux/library/l-pow-dynamic/ Service and productivity tools for Linux on POWER can be found at About the Authors John Engel is a Linux technical consultant for the IBM eserver Solutions Enablement organization at IBM. He is based in Rochester, MN. John's main role is to help solution developers bring their applications to Linux on POWER. While working at IBM, he has also held various positions in Linux software development. Brent Baude is a Linux consultant and Team Lead for the IBM eserver Solutions Enablement organization at IBM. He is based in Rochester, MN. Brent s main role is to help solution developers bring their applications to Linux on POWER. In the past, he has also held various positions in the iseries development labs. Brent also proudly serves as a Gentoo developer focusing on the ppc64 implementation of Gentoo. Trademarks and special notices IBM Corporation All rights reserved. References in this document to IBM products or services do not imply that IBM intends to make them available in every country. The following terms are trademarks of International Business Machines Corporation in the United States, other countries, or both: eserver IBM OpenPower 17

18 POWER POWER5 Red Hat, the Red Hat "Shadow Man" logo, and all Red Hat-based trademarks and logos are trademarks or registered trademarks of Red Hat, Inc., in the United States and other countries. UNIX is a registered trademark of The Open Group in the United States and other countries. Linux is a trademark of Linus Torvalds in the United States, other countries, or both. Other company, product or service names may be trademarks or service marks of others. Information is provided "AS IS" without warranty of any kind. All customer examples described are presented as illustrations of how those customers have used IBM products and the results they may have achieved. Actual environmental costs and performance characteristics may vary by customer. Information concerning non-ibm products was obtained from a supplier of these products, published announcement material, or other publicly available sources and does not constitute an endorsement of such products by IBM. Sources for non-ibm list prices and performance numbers are taken from publicly available information, including vendor announcements and vendor worldwide homepages. IBM has not tested these products and cannot confirm the accuracy of performance, capability, or any other claims related to non-ibm products. Questions on the capability of non-ibm products should be addressed to the supplier of those products. All statements regarding IBM future direction and intent are subject to change or withdrawal without notice, and represent goals and objectives only. Contact your local IBM office or IBM authorized reseller for the full text of the specific Statement of Direction. Some information addresses anticipated future capabilities. Such information is not intended as a definitive statement of a commitment to specific levels of performance, function or delivery schedules with respect to any future products. Such commitments are only made in IBM product announcements. The information is presented here to communicate IBM's current investment and development activities as a good faith effort to help with our customers' future planning. Performance is based on measurements and projections using standard IBM benchmarks in a controlled environment. The actual throughput or performance that any user will experience will vary depending upon considerations such as the amount of multiprogramming in the user's job stream, the I/O configuration, the storage configuration, and the workload processed. Therefore, no assurance can be given that an individual user will achieve throughput or performance improvements equivalent to the ratios stated here. Photographs shown are of engineering prototypes. Changes may be incorporated in production models. 18