mtpti5iD/redhat-docs_dataset huggingface dataset:
Chapter 4. Basic configuration options of Shenandoah garbage collector Shenandoah garbage collector (GC) has the following basic configuration options: -Xlog:gc Print the individual GC timing. -Xlog:gc+ergo Print the heuristics decisions, which might shed light on outliers, if any. -Xlog:gc+stats Print the summary table on Shenandoah internal timings at the end of the run. It is best to run this with logging enabled. This summary table conveys important information about GC performance. Heuristics logs are useful to figure out GC outliers. -XX:+AlwaysPreTouch Commit heap pages into memory and helps to reduce latency hiccups. -Xms and -Xmx Making the heap non-resizeable with -Xms = -Xmx reduces difficulties with heap management. Along with AlwaysPreTouch , the -Xms = -Xmx commit all memory on startup, which avoids difficulties when memory is finally used. -Xms also defines the low boundary for memory uncommit, so with -Xms = -Xmx all memory stays committed. If you want to configure Shenandoah for a lower footprint, then setting lower -Xms is recommended. You need to decide how low to set it to balance the commit/uncommit overhead versus memory footprint. In many cases, you can set -Xms arbitrarily low. -XX:+UseLargePages Enables hugetlbfs Linux support. -XX:+UseTransparentHugePages Enables huge pages transparently. With transparent huge pages, it is recommended to set /sys/kernel/mm/transparent_hugepage/enabled and /sys/kernel/mm/transparent_hugepage/defrag to madvise . When running with AlwaysPreTouch , it will also pay the defrag tool costs upfront at startup. -XX:+UseNUMA While Shenandoah does not support NUMA explicitly yet, it is a good idea to enable NUMA interleaving on multi-socket hosts. Coupled with AlwaysPreTouch , it provides better performance than the default out-of-the-box configuration. -XX:-UseBiasedLocking There is a tradeoff between uncontended (biased) locking throughput, and the safepoints JVM does to enable and disable them. For latency-oriented workloads, turn biased locking off. -XX:+DisableExplicitGC Invoking System.gc() from user code forces Shenandoah to perform additional GC cycle. It usually does not harm, as -XX:+ExplicitGCInvokesConcurrent gets enabled by default, which means the concurrent GC cycle would be invoked, not the STW Full GC. Revised on 2024-05-09 14:54:37 UTC

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Chapter 17. Accessing Red Hat Product Documentation Red Hat Product Documentation located at https://access.redhat.com/site/documentation/ serves as a central source of information. It is currently translated in 23 languages, and for each product, it provides different kinds of books from release and technical notes to installation, user, and reference guides in HTML , PDF , and EPUB formats. Below is a brief list of documents that are directly or indirectly relevant to this book. Red Hat Developer Toolset Red Hat Developer Toolset 12.1 Release Notes - The Release Notes for Red Hat Developer Toolset 12.1 contain more information. Using Red Hat Software Collections Container Images - The Using Red Hat Software Collections Container Images provides instructions for obtaining, configuring, and using container images that are shipped with Red Hat Software Collections, including the Red Hat Developer Toolset container images. Red Hat Software Collections Packaging Guide - The Software Collections Packaging Guide explains the concept of Software Collections and documents how to create, build, and extend them. Red Hat Enterprise Linux Red Hat Enterprise Linux 7 Developer Guide - The Developer Guide for Red Hat Enterprise Linux 7 provides more information about libraries and runtime support, compiling and building, debugging, and profiling. Red Hat Enterprise Linux 7 Installation Guide - The Installation Guide for Red Hat Enterprise Linux 7 explains how to obtain, install, and update the system. Red Hat Enterprise Linux 7 System Administrator's Guide - The System Administrator's Guide for Red Hat Enterprise Linux 7 documents relevant information regarding the deployment, configuration, and administration of Red Hat Enterprise Linux 7.

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B.7. Virtual network default has not been started Symptom Normally, the configuration for a virtual network named default is installed as part of the libvirt package, and is configured to autostart when libvirtd is started. If the default network (or any other locally-created network) is unable to start, any virtual machine configured to use that network for its connectivity will also fail to start, resulting in this error message: Investigation One of the most common reasons for a libvirt virtual network's failure to start is that the dnsmasq instance required to serve DHCP and DNS requests from clients on that network has failed to start. To determine if this is the cause, run virsh net-start default from a root shell to start the default virtual network. If this action does not successfully start the virtual network, open /var/log/libvirt/libvirtd.log to view the complete error log message. If a message similar to the following appears, the problem is likely a systemwide dnsmasq instance that is already listening on libvirt 's bridge, and is preventing libvirt 's own dnsmasq instance from doing so. The most important parts to note in the error message are dnsmasq and exit status 2 : Solution If the machine is not using dnsmasq to serve DHCP for the physical network, disable dnsmasq completely. If it is necessary to run dnsmasq to serve DHCP for the physical network, edit the /etc/dnsmasq.conf file. Add or uncomment the first line, as well as one of the two lines following that line. Do not add or uncomment all three lines: bind-interfaces interface= name_of_physical_interface listen-address= chosen_IP_address After making this change and saving the file, restart the systemwide dnsmasq service. , start the default network with the virsh net-start default command. Start the virtual machines.

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Virtual network default has not been started
Could not start virtual network default : internal error Child process (/usr/sbin/dnsmasq --strict-order --bind-interfaces --pid-file=/var/run/libvirt/network/ default .pid --conf-file= --except-interface lo --listen-address 192.168.122.1 --dhcp-range 192.168.122.2,192.168.122.254 --dhcp-leasefile=/var/lib/libvirt/dnsmasq/ default .leases --dhcp-lease-max=253 --dhcp-no-override) status unexpected: exit status 2
bind-interfaces interface= name_of_physical_interface listen-address= chosen_IP_address
Chapter 40. Desktop Wayland available as a Technology Preview The Wayland display server protocol is available in Red Hat Enterprise Linux as a Technology Preview with the dependent packages required to enable Wayland support in GNOME, which supports fractional scaling. Wayland uses the libinput library as its input driver. The following features are currently unavailable or do not work correctly: Multiple GPU support is not possible at this time. The NVIDIA binary driver does not work under Wayland . The xrandr utility does not work under Wayland due to its different approach to handling, resolutions, rotations, and layout. Screen recording, remote desktop, and accessibility do not always work correctly under Wayland . No clipboard manager is available. It is currently impossible to restart GNOME Shell under Wayland . Wayland ignores keyboard grabs issued by X11 applications, such as virtual machines viewers. (BZ#1481411) Fractional Scaling available as a Technology Preview Starting with Red Hat Enterprise Linux 7.5, GNOME provides, as a Technology Preview, fractional scaling to address problems with monitors whose DPI lies in the middle between lo (scale 1) and hi (scale 2). Due to technical limitations, fractional scaling is available only on Wayland. (BZ# 1481395 )

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Chapter 3. Red Hat build of OpenJDK 17.0.4.1 release notes Review the following release note to understand changes from the Red Hat build of OpenJDK 17.0.4.1 patch release: Fixed issue with the C2 JIT compiler The Red Hat build of OpenJDK 17.0.4.1 release fixes a regression issue with the C2 Just-In-Time (JIT) compiler, which caused the HotSpot JVM to unexpectedly crash. See, JDK-8292396 (JDK Bug System) Advisories related to the Red Hat build of OpenJDK 17.0.4.1 release The following advisories have been issued to bug fixes and CVE fixes included in this release: RHBA-2022:6293-01 RHBA-2022:6350-02

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function::printk Name function::printk - Send a message to the kernel trace buffer Synopsis Arguments level an integer for the severity level (0=KERN_EMERG ... 7=KERN_DEBUG) msg The formatted message string Description Print a line of text to the kernel dmesg/console with the given severity. An implicit end-of-line is added. This function may not be safely called from all kernel probe contexts, so is restricted to guru mode only.

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printk(level:long,msg:string)
13.11. Changing Behavior when Pressing the Power Button in Graphical Target Mode When the machine is booted to a graphical login screen or user session, hitting the power button makes the machine suspend by default. This happens both in cases when the user presses the power button physically or when pressing a virtual power button from a remote console. To achieve a different behavior when pressing the power button, set the function of this button with dconf. For example, if you want the system to shutdown after pressing the power button, use the following procedure: Procedure 13.11. Using dconf to configure the system to shutdown after pressing the power button Create a local database for system-wide settings in the /etc/dconf/db/local.d/01-power file: Override the user's setting and prevent the user from changing it in the /etc/dconf/db/local.d/locks/01-power file: Update the system databases: Log out and back in again before the system-wide settings take effect. This configuration initiates a system shutdown after pressing the power button. To configure the system differently, you can set the behavior of particular buttons. Options for particular buttons nothing does nothing suspend suspends the system hibernate hibernates the system interactive shows a pop-up query asking the user what to do With interactive mode, the system powers off automatically after 60 seconds when hitting the power button. However, you can choose a different behavior from the pop-up query as shown in the figure below. Figure 13.2. Pop-up query for interactive mode

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[org/gnome/settings-daemon/plugins/power] power-button-action='interactive'
/org/gnome/settings-daemon/plugins/power/power-button-action
dconf update
4.5. Testing the Resource Configuration If the Samba configuration was successful, you should be able to mount the Samba share on a node in the cluster. The following example procedure mounts a Samba share. Add an existing user in the cluster node to the smbpasswd file and assign a password. In the following example, there is an existing user smbuser . Mount the Samba share: Check whether the file system is mounted: To check for Samba recovery, perform the following procedure. Manually stop the CTDB resource with the following command: After you stop the resource, the system should recover the service. Check the cluster status with the pcs status command. You should see that the ctdb-clone resource has started, but you will also see a ctdb_monitor failure. To clear this error from the status, enter the following command on one of the cluster nodes:

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smbpasswd -a smbuser New SMB password: Retype new SMB password: Added user smbuser
mkdir /mnt/sambashare mount -t cifs -o user=smbuser //198.162.1.151/public /mnt/sambashare Password for smbuser@//198.162.1.151/public: ********
mount | grep /mnt/sambashare //198.162.1.151/public on /mnt/sambashare type cifs (rw,relatime,vers=1.0,cache=strict,username=smbuser,domain=LINUXSERVER,uid=0,noforceuid,gid=0,noforcegid,addr=10.37.167.205,unix,posixpaths,serverino,mapposix,acl,rsize=1048576,wsize=65536,echo_interval=60,actimeo=1)
pcs resource debug-stop ctdb
pcs status Clone Set: ctdb-clone [ctdb] Started: [ z1.example.com z2.example.com ] Failed Actions: * ctdb_monitor_10000 on z1.example.com 'unknown error' (1): call=126, status=complete, exitreason='CTDB status call failed: connect() failed, errno=111', last-rc-change='Thu Oct 19 18:39:51 2017', queued=0ms, exec=0ms
pcs resource cleanup ctdb-clone
Chapter 127. KafkaBridgeProducerSpec schema reference Used in: KafkaBridgeSpec Full list of KafkaBridgeProducerSpec schema properties Configures producer options for the Kafka Bridge as keys. The values can be one of the following JSON types: String Number Boolean Exceptions You can specify and configure the options listed in the Apache Kafka configuration documentation for producers . However, AMQ Streams takes care of configuring and managing options related to the following, which cannot be changed: Kafka cluster bootstrap address Security (encryption, authentication, and authorization) Consumer group identifier Properties with the following prefixes cannot be set: bootstrap.servers sasl. security. ssl. If the config property contains an option that cannot be changed, it is disregarded, and a warning message is logged to the Cluster Operator log file. All other supported options are forwarded to Kafka Bridge, including the following exceptions to the options configured by AMQ Streams: Any ssl configuration for supported TLS versions and cipher suites Example Kafka Bridge producer configuration apiVersion: kafka.strimzi.io/v1beta2 kind: KafkaBridge metadata: name: my-bridge spec: # ... producer: config: acks: 1 delivery.timeout.ms: 300000 # ... Important The Cluster Operator does not validate keys or values in the config object. If an invalid configuration is provided, the Kafka Bridge deployment might not start or might become unstable. In this case, fix the configuration so that the Cluster Operator can roll out the new configuration to all Kafka Bridge nodes. 127.1. KafkaBridgeProducerSpec schema properties Property Description config The Kafka producer configuration used for producer instances created by the bridge. Properties with the following prefixes cannot be set: ssl., bootstrap.servers, sasl., security. (with the exception of: ssl.endpoint.identification.algorithm, ssl.cipher.suites, ssl.protocol, ssl.enabled.protocols). map

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apiVersion: kafka.strimzi.io/v1beta2 kind: KafkaBridge metadata: name: my-bridge spec: # producer: config: acks: 1 delivery.timeout.ms: 300000 #
Chapter 3. Networking QFQ queuing discipline In Red Hat Enterprise Linux 6.3, the tc utility has been updated to work with the Quick Fair Scheduler (QFQ) kernel features. Users can now take advantage of the new QFQ traffic queuing discipline from userspace. This feature is considered a Technology Preview. rdma_bw and rdma_last utilities deprecated The rdma_bw and rdma_lat utilities (provided by the perftest package) are now deprecated and will be removed from the perftest package in a future update. Users should use the following utilities instead: ib_write_bw , ib_write_lat , ib_read_bw , and ib_read_lat . Enhancements in the configuration tool for IBM System z network devices With Red Hat Enterprise Linux 6.3, the System z qethconf tool provides information messages when a change of attributes did not work as expected. IPv6 support for qetharp tool for IBM System z Red Hat Enterprise Linux 6.3 adds IPv6 support to the qetharp tool for inspection and modification of the ARP cache of HiperSockets (real and virtual) operated in layer 3 mode. For real HiperSockets, the tool queries and shows the IPv6 address, and for guest LAN HiperSockets, it queries and shows IPv6 to MAC address mappings. Maximum number of session slots In Red Hat Enterprise Linux 6.3, NFSv4 introduces a module/kernel boot parameter, nfs.max_session_slots , which sets the maximum number of session slots the NFS client will attempt to negotiate with the server. This limits the number of simultaneous RPC requests that the client can send to the NFSv4 server. Note that setting this value higher than max_tcp_slot_table_limit has no effect.

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23.15.4. Create LVM Logical Volume Important LVM initial set up is not available during text-mode installation. If you need to create an LVM configuration from scratch, establish another SSH connection to the installation image with the root user and run the lvm command. Logical Volume Management (LVM) presents a simple logical view of underlying physical storage space, such as a hard drives or LUNs. Partitions on physical storage are represented as physical volumes that can be grouped together into volume groups . Each volume group can be divided into multiple logical volumes , each of which is analogous to a standard disk partition. Therefore, LVM logical volumes function as partitions that can span multiple physical disks. To read more about LVM, refer to the Red Hat Enterprise Linux Deployment Guide . Note, LVM is only available in the graphical installation program. LVM Physical Volume Choose this option to configure a partition or device as an LVM physical volume. This option is the only choice available if your storage does not already contain LVM Volume Groups. This is the same dialog that appears when you add a standard partition - refer to Section 23.15.2, "Adding Partitions" for a description of the available options. Note, however, that File System Type must be set to physical volume (LVM) Figure 23.42. Create an LVM Physical Volume Make LVM Volume Group Choose this option to create LVM volume groups from the available LVM physical volumes, or to add existing logical volumes to a volume group. Figure 23.43. Make LVM Volume Group To assign one or more physical volumes to a volume group, first name the volume group. Then select the physical volumes to be used in the volume group. Finally, configure logical volumes on any volume groups using the Add , Edit and Delete options. You may not remove a physical volume from a volume group if doing so would leave insufficient space for that group's logical volumes. Take for example a volume group made up of two 5 GB LVM physical volume partitions, which contains an 8 GB logical volume. The installer would not allow you to remove either of the component physical volumes, since that would leave only 5 GB in the group for an 8 GB logical volume. If you reduce the total size of any logical volumes appropriately, you may then remove a physical volume from the volume group. In the example, reducing the size of the logical volume to 4 GB would allow you to remove one of the 5 GB physical volumes. Make Logical Volume Choose this option to create an LVM logical volume. Select a mount point, file system type, and size (in MB) just as if it were a standard disk partition. You can also choose a name for the logical volume and specify the volume group to which it will belong. Figure 23.44. Make Logical Volume

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9.6. Graphics Devices The SPICE or VNC graphics protocols can be used to connect to the emulated graphics devices. You can select a Video Type in the Administration Portal: QXL : Emulates a para-virtualized video card that works best with QXL guest drivers VGA : Emulates a dummy VGA card with Bochs VESA extensions Note Virtual machines using VNC and Cirrus, which are imported from environments with a 3.6 compatibility level or earlier, will be converted to VNC and VGA automatically. You can update the graphics protocols and video types in the Administration Portal. See Virtual Machine Console Settings Explained in the Virtual Machine Management Guide for more information.

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11.2. Known Issues cURL is a tool for getting files from FTP, HTTP, Gopher, Telnet, and Dict servers, using any of the supported protocols. The cURL API, and consequently, the python bindings for cURL, do not provide textual messages for errors. Therefore, all applications that use the python bindings for cURL will return errors in formats such as: instead of more useful messages such as: cURL error codes can be manually interpreted by reading the /usr/include/curl/curl.h file. Due to a deficiency in java-1.6.0-ibm-plugin for AMD64 and Intel 64, IBM Java 6 Web Start cannot open JNLP files. This affects file management tools and WWW browsers. To work around this open JNLP files using the command: Note that 32-bit packages are not affected by this issue. Under some circumstances on the PPC64 architecture, Ruby does not save the context correctly when switching threads. Consequently, when a thread is restored it has a stale value which might return a architecture fault. Under some circumstances, libdfp encounters an issue converting some values from string to DFP with the conversion command strtod32. The strtod64 and strtod128 commands do work correctly.

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Pycurl Error 6 - ""
Pycurl Error 6 - "Could not resolve hostname: blah.example.com"
/usr/lib/jvm/jre-1.6.0-ibm.x86_64/bin/javaws file.jnpl
C.18. RpcManager org.infinispan.remoting.rpc.RpcManagerImpl The RpcManager component manages all remote calls to remote cache instances in the cluster. Note The RpcManager component is only available in clustered mode. Table C.28. Attributes Name Description Type Writable averageReplicationTime The average time spent in the transport layer, in milliseconds. long No committedViewAsString Retrieves the committed view. String No pendingViewAsString Retrieves the pending view. String No replicationCount Number of successful replications. long No replicationFailures Number of failed replications. long No successRatio Successful replications as a ratio of total replications. String No successRatioFloatingPoint Successful replications as a ratio of total replications in numeric double format. double No statisticsEnabled Enables or disables the gathering of statistics by this component. boolean Yes Table C.29. Operations Name Description Signature resetStatistics Resets statistics gathered by this component. void resetStatistics() setStatisticsEnabled Whether statistics should be enabled or disabled (true/false) void setStatisticsEnabled(boolean enabled) 23149%2C+Administration+and+Configuration+Guide-6.628-06-2017+13%3A51%3A02JBoss+Data+Grid+6Documentation6.6.1 Report a bug

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Chapter 5. Encryption token is deleted or expired Use this procedure to update the token if the encryption token for your key management system gets deleted or expires. Prerequisites Ensure that you have a new token with the same policy as the deleted or expired token Procedure Log in to OpenShift Container Platform Web Console. Click Workloads Secrets To update the ocs-kms-token used for cluster wide encryption: Set the Project to openshift-storage . Click ocs-kms-token Actions Edit Secret . Drag and drop or upload your encryption token file in the Value field. The token can either be a file or text that can be copied and pasted. Click Save . To update the ceph-csi-kms-token for a given project or namespace with encrypted persistent volumes: Select the required Project . Click ceph-csi-kms-token Actions Edit Secret . Drag and drop or upload your encryption token file in the Value field. The token can either be a file or text that can be copied and pasted. Click Save . Note The token can be deleted only after all the encrypted PVCs using the ceph-csi-kms-token have been deleted.

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1.7. Red Hat Gluster Storage Support Matrix This section lists all the supported Red Hat Enterprise Linux version for a particular Red Hat Gluster Storage release. Table 1.7. Red Hat Gluster Storage Support Matrix Red Hat Enterprise Linux version Red Hat Gluster Storage version 6.5 3.0 6.6 3.0.2, 3.0.3, 3.0.4 6.7 3.1, 3.1.1, 3.1.2 6.8 3.1.3 6.9 3.2 6.9 3.3 6.9 3.3.1 6.10 3.4, 3.5 7.1 3.1, 3.1.1 7.2 3.1.2 7.2 3.1.3 7.3 3.2 7.4 3.2 7.4 3.3 7.4 3.3.1 7.5 3.3.1, 3.4 7.6 3.3.1, 3.4 7.7 3.5, 3.5.1 7.8 3.5.1, 3.5.2 7.9 3.5.3, 3.5.4, 3.5.5, 3.5.6, 3.5.7 8.2 3.5.2, 3.5.3 8.3 3.5.3 8.4 3.5.4 8.5 3.5.5, 3.5.6 8.6 3.5.7

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