Posts Tagged ‘Oracle’

Attach multiple Oracle ASM snapshots to the same host

Thursday, September 12th, 2013

The goal – connecting multiple Oracle ASM snapshots (same source LUNs, of course) to the same machine. The next process will demonstrate how to do it.

Problem: ASM disks use a disk label called ASMLib to maintain access even when the logical disk path might change (like adding a LUN with a lower ID and rebooting the server). This solves a major problem which was experienced with RAW devices, when order changed, and the ‘wrong’ disks took the place of others. ASM labels are a vital part in managing ASM disks and ASM DiskGroups. Also – the ASM DiskGroup name should be unique. You cannot have multiple DiskGroups with the same name.

Limitations – you cannot connect the snapshot LUNs to the same server which has access to the source LUNs.

Process:

  1. Take a snapshot of the source LUN. If the ASM DiskGroup spans across several LUNs, you must create a consistency group (each storage device has its own lingo for the task).
  2. Map the snapshots to the target server (EMC – prepare EMC Snapshot Mount Points (SMP) in advance. Other storage devices – depending)
  3. Perform partprobe on all target servers.
  4. Run ‘service oracleasm scandisks‘ to scan for the new ASM disk labels. We will need to change them now, so that the additional snapshot will not use duplicate ASM labels.
  5. For each of the new ASM disks, run ‘service oracleasm force-renamedisk SRC_NAME TGT_NAME‘. You will want to rename the source name (SRC_NAME) to a unique target name, with some correlation to the snapshot name/purpose. This is the reasonable way of making some sense of a possibly very messy setup.
  6. As the Oracle user, with the correct PATH variables ($ORACLE_HOME should point to the CRS_HOME) and the right ORACLE_SID (for example – +ASM1), run: ‘renamedg phase=both dgname=SRC_DG_NAME newdgname=NEW_DG_NAME verbose=true‘. The value ‘SRC_DG_NAME’ represents the original (on the source) DiskGroup name, and the NEW_DG_NAME represents the new name. Much like when renaming the disks – the name should have some relationship with either the snapshot name, so you can find your hands and legs in this mess (again – imagine having six snapshots, each of a DiskGroup with four LUNs. Now – this is a mess).
  7. You can now mount the DiskGroup (named NEW_DG_NAME in my example) on both nodes

Assumptions:

  1. Oracle GI is up and running all through this process
  2. I tested it with Oracle 11.2.0.3. Other versions of 11.2.0.x might work, I have no clue about previous 11.1.x versions, or any earlier versions.
  3. It was tested on Linux. My primary work platform. It was, to be exact, on RHEL 6.4, but it should work just the same on any RHEL-like platform. I believe it will work on other Linux platforms. I have no clue about running it on any other Unix/Windows platform.
  4. The DiskGroup should not be mounted (no reason for it to be mounted right on discovery). Do not manually mount it prior to performing this procedure.

Good luck, and post a comment if you find this explanation either unclear, or if you encounter any problem.

 

 

 

BackupExec 2012 (14) on newer Linux

Tuesday, August 6th, 2013

In particular – Oracle UEK, which “claims” to be 2.6.39-xxx, but is actually 3.0.x with a lower version number. Several misbehaviors (or differences) of version 3 can be found. One of them is related to BackupExec. The service would not start on OEL6 with UEK kernels. The cause of it is an incorrect use of a function – getIfAddrs. Everything can be seen in this amazing post. The described patch works, at least to allow the service to start. Check out the comments for some insights about how to identify the correct call.

I am re-posting it here, so it can be found for Oracle Universal Enterprise Kernel (UEK) as well.

Things to remember…

Monday, October 24th, 2011

As my work takes me to various places (where technology is concerned), I collect lots of browser tab of things I want to keep for later reference.
I have to admit, sadly, that I lack the time to sort them out, to make a real good and nice post about them. I do not want to lose them, however, so I am posting now those which I find or found in the past as more useful to me. I might expand either of them one day into a full post, or elaborate further on them. Either or none. For now – let’s clean up some tab space:
Reading IPMI sensors. Into Cacti, and into Nagios, with some minor modifications by myself (to be disclosed later, I believe):
Cacti
Nagios
This is somewhat info of the plugin check_ipmi_sensor
And its wiki (in German. Use Google for translation)
XenServer checks:
check_xen_pool
Checking XenServer using NRPE
But I did not care about Dom0 performance parameters, as they meant very little regarding the hypervisor’s behavior. So I have combined into it the following XenServer License Check. Unfortunately, I could run it only on the XenServer domain0, due to python version limitations on my Cacti /Nagios server.
You can obtain XenServer SDK
This plugin looks interesting for various XenServer checks, but I have never tried it myself.
Backing up (exporting) XenServer VMs as a scheduled task. I have had it modified extensively to match my requirements, but I am allowed to, it has some of its sources based on my blog 🙂
Installing Dell OpenManage on XenServer 5.6.1, and the nice thing is that it works fine on XenServer 6 as well.
Oracle ASM recovery tips . One day I will take it further, and investigate possible human errors and methods of fixing them. Experience, they say, has a value 🙂
A guide dealing with changing from raw to block devices in Oracle ASM . This is only a small part of it, but it’s the thing that interests me.
Understanding Steal Time in Linux Xen-based VMs.
Because I always forget, and I’m too lazy to search again and again (and reach the same page again and again): Upgrading PHP to 5.2 on Centos 5
And last – a very nice remote-control software fomr my Android phone. Don’t leave home without it. Seriously.

Reduced to only 23 tabs is excellent. This was a very nice job, and these links will be useful. To me, for sure. I hope that to you as well.

Oracle VM post-install check list

Saturday, May 22nd, 2010

Following my experience with OracleVM, I am adding my post-install steps for your pleasure. These steps are not mandatory, by design, but will help you get up and running faster and easier. These steps are relevant to Oracle VM 2.2, but might work for older (and newer) versions as well.

Define bonding

You should read more about it in my past post.

Define storage multipathing

You can read about it here.

Define NTP

Define NTP servers for your Oracle VM host. Make sure the daemon ‘ntpd’ is running, and following an initial time update, via

ntpdate -u <server>

to set the clock right initially, perform a sync to the hardware clock, for good measures

hwclock –systohc

Make sure NTPD starts on boot:

chkconfig ntpd on

Install Linux VM

If the system is going to be stand-alone, you might like to run your VM Manager on it (we will deal with issues of it later). To do so, you will need to install your own Linux machine, since Oracle supplied image fails (or at least – failed for me!) for no apparent reason (kernel panic, to be exact, on a fully MD5 checked image). You could perform this action from the command line by running the command

virt-install -n linux_machine -r 1024 -p –nographics -l nfs://iso_server:/mount

This directive installs a VM called “linux_machine” from nfs iso_server:/mount, with 1GB RAM. You will be asked about where to place the VM disk, and you should place it in /OVS/running_pool/linux_machine , accordingly.

It assumes you have DHCP available for the install procedure, etc.

Install Oracle VM Manager on the virtual Linux machine

This should be performed if you select to manage your VMs from a VM. This is a bit tricky, as you are recommended not to do so if you designing HA-enabled server pool.

Define autostart to all your VMs

Or, at least, those you want to auto start. Create a link from /OVS/running_pool/<VM_NAME>/vm.cfg to /etc/xen/auto/

The order in which ‘ls’ command will see them in /etc/xen/auto/ is the order in which they will be called.

Disable or relocate auto-suspending

Auto-suspend is cool, but your default Oracle VM installation has shortage of space under /var/lib/xen/save/ directory, where persistent memory dumps are kept.  On a 16GB RAM system, this can get pretty high, which is far more than your space can contain.

Either increase the size (mount something else there, I assume), or edit /etc/sysconfig/xendomains and comment the line  with the directive XENDOMAINS_SAVE= . You could also change the desired path to somewhere you have enough space on.

Hashing this directive will force regular shutdown to your VMs following a power off/reboot command to the Oracle VM.

Make sure auto-start VMs actually start

This is an annoying bug. For auto-start of VMs, you need /OVS up and available. Since it’s OCFS2 file system, it takes a short while (being performed by ovs-agent).

Since ovs-agent takes a while, we need to implement a startup script after it and before xendomains. Since both are markes “S99” (check /etc/rc3.d/ for details), we would add a script called “sleep”.

The script should be placed in /etc/init.d/

#!/bin/bash
#
# sleep     Workaround Oracle VM delay issues
#
# chkconfig: 2345 99 99
# description: Adds a predefined delay to the initialization process
#

DELAY=60

case "$1" in
start) sleep $DELAY
;;
esac
exit 0

Place the script as a file called “sleep” (omit the suffix I added in this post), set it to be executable, and then run

chkconfig –add sleep

This will solve VM startup problems.

Fix /etc/hosts file

If you are into multi-server pool, you will need that the host name would not be defined to 127.0.0.1 address. By default, Oracle VM defines it to match 127.0.0.1, which will result in a poor attempt to create multi-server pool.

This is all I have had in mind for now. It should solve most new-comer issues with Oracle VM, and allow you to make good use of it. It’s a nice system, albeit it’s ugly management.

Update the OracleVM

You could use Oracle’s unbreakable network, if you are a paying customer, or you could use the Public Yum Server for your system.

Updates to Oracle VM Manager

If you won’t use Oracle Grid Control (Enterprise Manager) to manage the pool, you will probably use Oracle VM Manager. You would need to update the ovs-console package, and you will probably want to add tightvnc-java package, so that IE users will be able to use the web-based VNC services. You would better grub these packages from here.

Oracle Clusterware as a 3rd party HA framework

Friday, June 12th, 2009

Oracle begin to push their Clusterware as a 3rd party HA framework. In this article we will review a quick example of how to do it. I will refer to this post as a quick-guide, as this is by no means any full-scale guide.

This article assumes you have installed Oracle Clusterware following one of the few links and guides available on the net. This quick-guide applies to both Clusterware 10 and Clusterware 11.

We will discuss the method of adding an additional NFS service on Linux.

In order to do so, you will need a shared storage – assuming the goal of the exercise is to supply the clients with a consistent storage services based on NFS. I, for myself, prefer to use OCFS2 as the choice file system for shared disks. This goes well with Oracle Clusterware, as this cluster framework does not handle disk mounts very well, and unless you are to write/search an agent which will make sure that every mount and umount behave correctly (you wouldn’t want to get a file system corruption, would you?), you will probably prefer to do the same. The lack of need to manage the disk mount actions will both save time on planned failover, and will guarantee storage safety. If you have not placed your CRS and Vote on OCFS2, you will need to install OCFS2 from here and here, and then to configure it. We will not discuss OCFS2 configuration in this post.

We will need to assume the following prerequisites:

  • Service-related IP address: 1.2.3.4. Netmask 255.255.255.248. You need this IP to be member of the same class as your public network card is.
  • Shared Storage: Formatted to OCFS2, and mounted on both nodes on /shared
  • Oracle Clusterware installed and working
  • Cluster nodes names are “node1” and “node2”
  • Have $CRS_HOME point to your CRS installation
  • Have $CRS_HOME/bin in your $PATH

We need to create the service-related IP resource first. I would recommend to have an entry in /etc/hosts for this IP address on both nodes. Assuming the public NIC is eth0, The command would be

crs_profile -create nfs_ip -t application -a $CRS_HOME/bin/usrvip -o oi=eth0,ov=1.2.3.4,on=255.255.255.248

Now you will need to set running permissions for the oracle user. In my case, the user name is actually “oracle”:

crs_setperm nfs_ip -o root
crs_serperm nfs_ip -u user:oracle:r-x

Test that you can start the service as the oracle user:

crs_start nfs_ip

Now we need to setup NFS. For this to work, we need to setup the NFS daemon first. Edit /etc/exports and add a line such as this:

/shared *(rw,no_root_sqush,sync)

Make sure that nfs service is disabled during startup:

chkconfig nfs off
chkconfig nfslock off

Now is the time to setup Oracle Clusterware for the task:

crs_profile -create share_nfs -t application -B /etc/init.d/nfs -d “Shared NFS” -r nfs_ip -a sharenfs.scr -p favored -h “node1 node2” -o ci=30,ft=3,fi=12,ra=5
crs_register share_nfs

Deal with permissions:

crs_setperms share_nfs -o root
crs_setperms share_nfs -u user:oracle:r-x

Fix the “sharenfs.scr” script. First, find it. It should reside in $CRS_HOME/crs/scripts if everything is OK. If not, you will be able to find it in $CRS_HOME using find.

Edit the “sharenfs.scr” script and modify the following variables which are defined relatively in the beginning of the script:

PROBE_PROCS=”nfsd”
START_APPCMD=”/etc/init.d/nfs start
START_APPCMD2=”/etc/init.d/nfslock start”
STOP_APPCMD=”/etc/init.d/nfs stop”
STOP_APPCMD2=”/etc/init.d/nfslock stop”

Copy the modified script file to the other node. Verify this script has execution permissions on both nodes.

Start the service as the oracle user:

crs_start sharenfs

Test the service. The following command should return the export path:

showmount -e 1.2.3.4

Relocate the service and test again:

crs_relocate -f sharenfs
showmount -e 1.2.3.4

Done. You now have HA NFS service above Oracle Clusterware framework.

I used this web page as a reference. I thank him for his great work!