Question: How to check the ring buffer slot values of each network interface? How much space or size does each slot have? For checking the ring buffer slot size, ethtool -g ethX can be used. Consider the below example for checking the ring buffer size for eth0: Example: # ethtool -g eth4 Ring parameters for eth4: Pre-set maximums: RX: 1024 RX Mini: 0 RX Jumbo: 0 TX: 2048 Current hardware settings: RX: 972 RX Mini: 0 RX … [Read more...] about How to check the ring buffer size of the network interface in CentOS/RHEL
CentOS/RHEL 6
How to Create a GFS2 Formatted Cluster File System
Global File System 2 (GFS2) Global File System 2 (GFS2) is a cluster file system interfacing directly with the kernel VFS layer. This means that the same file system can be mounted and used by multiple cluster nodes simultaneously, while still providing a full regular file system, including features such as support for POSIX ACLs, extended attributes, and quotas. To accomplish this, every node accessing a GFS2 file system uses the cluster infrastructure provided by Corosync and Pacemaker to … [Read more...] about How to Create a GFS2 Formatted Cluster File System
Beginners Guide to Global File System 2 (GFS2)
Global File System 2 (GFS2) Global File System 2 (GFS2) is a cluster file system interfacing directly with the kernel VFS layer. This means that the same file system can be mounted and used by multiple cluster nodes simultaneously, while still providing a full regular file system, including features such as support for POSIX ACLs, extended attributes, and quotas. To accomplish this, every node accessing a GFS2 file system uses the cluster infrastructure provided by Corosync and Pacemaker to … [Read more...] about Beginners Guide to Global File System 2 (GFS2)
Managing Clustered Logical Volumes in RHEL CLuster (pacemaker)
Clustered LVM Clustered LVM allows the use of regular LVM volume groups and logical volumes on shared storage. In a cluster configured with clustered LVM, a volume group and its logical volumes are accessible to all cluster nodes at the same time. With clustered LVM, administrators can use the management benefits of LVM in conjunction with a shared file system like GFS2, for scenarios such as making virtual machine images inside logical volumes available to all cluster nodes. The … [Read more...] about Managing Clustered Logical Volumes in RHEL CLuster (pacemaker)
How to Configure Logical Volume Manager for Cluster File System
LVM review Logical Volume Management (LVM) provides administrators with a powerful storage virtualization framework. One or more data bearers (physical volumes) get aggregated into a storage pool (volume group), from which volumes can get carved to act as block devices (logical volumes). LVM also allows for the striping and/or mirroring of data between physical volumes. The following graphic shows the basic steps of creating a volume group and logical volumes. Just like dm-multipath, LVM … [Read more...] about How to Configure Logical Volume Manager for Cluster File System
How to monitor the status of dm-multipathing and multipath devices (path groups) in Linux
Monitoring The multipath command can be used to monitor the status of multipaths. When used with one -l option, it will show a quick overview of multipath topologies. If the -l option is specified twice (-ll), it will also perform a check on all paths to see if it is active. If everything is fine, a path will be reported as active ready. The output of multipath -ll provides information on each discovered multipath device. This is comprised of three sections. The sections provide information … [Read more...] about How to monitor the status of dm-multipathing and multipath devices (path groups) in Linux
Understanding Linux multipath (dm-multipath)
What is multipathing? Multipathing allows the combination of multiple physical connections between a server and a storage array into one virtual device. This can be done to provide a more resilient connection to your storage (a path going down will not hamper connectivity), or to aggregate storage bandwidth for improved performance. As an example, the server in the following diagram has two HBAs, each connected to a separate Fibre Channel switch, which in turn are connected to separate … [Read more...] about Understanding Linux multipath (dm-multipath)
Managing iSCSI Timeouts Settings in Linux
After reading this post, you should be able to: Tune NOP-Out interval and timeout settings for improved network monitoring. Manage recovery timeout setting on iSCSI initiators. NOP-Out interval and timeout Communication between iSCSI initiators and targets are sent in iSCSI protocol data units (PDUs). Request PDUs are sent by initiators, while response PDUs are sent by targets. The Opcode field in the iSCSI POU header indicates the iSCSI POU type. There are two categories of … [Read more...] about Managing iSCSI Timeouts Settings in Linux
What is stunnel and how to configure it on CentOS/RHEL 5,6
stunnel is designed to work as SSL encryption wrapper between remote clients and local (inetd-startable) or remote servers. The concept is that having non-SSL aware daemons running on your system you can easily set them up to communicate with clients over secure SSL channels. SERVER CONFIGURATION 1. Install stunnel package: # yum install stunnel 2. Edit /etc/stunnel/stunnel.conf: # vi /etc/stunnel/stunnel.conf output = /var/log/stunnel.log cert = … [Read more...] about What is stunnel and how to configure it on CentOS/RHEL 5,6
How to enable faillog with pam_tally2 in CentOS/RHEL 6 and 7
In CentOS/RHEL 6, faillog no longer exists. This is because CentOS/RHEL 6 makes pam_tally2 the default, which no longer uses faillog as pam_tally did. 1. Add the following lines to /etc/pam.d/system-auth and also to /etc/pam.d/password-auth as this will be included for remote logins. The first line goes at the top of the auth section, the second line at the top of the account section: auth required pam_tally2.so deny=3 onerr=fail unlock_time=900 auth required … [Read more...] about How to enable faillog with pam_tally2 in CentOS/RHEL 6 and 7