Storage level snapshot are an incredibly fast and space efficient method to create usable clones of an Oracle database. In this post we’ll create a storage-level snapshot of a Oracle database using a Dell Powerstore storage array. Our database spans two ASM diskgroups, and will be mounted to a second server.
Category Archives: Linux
Create ASM diskgroups with Dell Powerstore
I recently got an opportunity to do some testing with a Dell Powerstore 5000T all-flash storage array, so I thought I would share some of the notes I made during my testing, for the benefit of any DBAs who might be using one to deliver ASM disks to their Oracle databases.
This will be part of a series of posts that focus on the management of Oracle and ASM with Powerstore, so consider this post as a foundational topic. Nothing especially earth shattering, but some solid points nonetheless.
Adding a GUI to Oracle Enterprise Linux from the local install media
I’ve made this mistake a few times now.
In my excitement to get a new copy of OEL installed, I manage to forget to select the version with the GUI. I reboot my VM, and am presented with a command-line login.
Of course I could just delete the VM and start over. Or I could follow the instructions available from several sites and blogs that explain a simple yum command to a public repo is all I need to add the missing graphical interface:
$ yum groupinstall "Server with GUI"
But more often than not, I am doing this in a company lab that is more locked down than Ft. Knox. Draconian network security mandates mean no public internet access, and it would be an act of Congress to get that changed.
EMC Unity Storage Performance testing with Oracle ASM and SLOB
I’ve been testing the new EMC Unity 600F all-flash storage array with an Oracle database to determine the impact of storage compression on Oracle I/O performance. To do this I have been using Kevin Closson’s SLOB tool.
SLOB is an excellent tool for testing I/O performance as seen by Oracle. Unlike Swingbench which mimics a real application and therefore spends much of its execution cycle on the server CPU, SLOB concentrates exclusively on generating I/O from the Oracle stack.
Conversely, don’t expect SLOB to generate meaningful data to test ranking or sorting operations inside of Oracle. SLOB generates entirely synthetic data that is meaningless from an application standpoint.
The following posts covers using SLOB to test I/O performance, and what was learned from the testing against the Unity 600F all-flash array.
Experimenting with ASM Filter Drivers
Oracle is moving away from ASMlib, and introducing ASM Filter Drivers as a replacement.
ASM Filter Drivers will handle consistent device naming and permissions, as well as filter out illegal IO to ASM devices to protect against rogue dd commands corrupting ASM disks.
Future plans include support for TRIM commands to enable thinly provisioned disks to reclaim deleted blocks without having to resort to the massively dangerous ASRU tool.
ASM Filter Drivers were introduced with Oracle 12.1.0.2, but the implementation is currently one massive kludge. By default on 12.1.0.2, OEL7 is not supported without a patch (patch 21053000). OEL6 UEK is also not supported without a patch (patch 18321597).
Note that the patches require OPatch 12.1.0.2, but Oracle Grid Infrastructrue 12.1.0.2 installs OPatch 12.1.0.1.3 so you have to patch the patcher (patch 6880880), so you can patch the Oracle software, to make Oracle ASM Filter Drivers work with Oracle’s own operating system kernel. Clear? Good!
You cannot install Filter Drivers by default. You have to migrate to them from UDEV or ASMlib.
Oracle 12.2 should hopefully fix this mess and make Filter Drivers actually usable, but in the meantime it might be fun to play with the new technology and see what it can do.
Relocating the OCR/Voting disks for a 12c RAC
There are many examples of this one, this is again more for my benefit than anyone else’s.
The following shows relocating the OCR and voting disks on a 12c RAC.
No downtime is needed. You only need to execute these commands on one node. Log in as root and source the Grid Infrastructure environment to make these changes:
UDEV rules for ASM disks on RHEL7
On this blog and elsewhere you will find UDEV rules examples for setting device ownership and naming consistency on older versions of Linux.
With RHEL7 some of the syntax has changed slightly.
This example was created using OEL7 with the Red Hat kernel, but should also work on Red Hat and CentOS.
Cleaning up a failed 12cR1 RAC install
The following shows how to clean up a failed 12cR1 RAC install on Linux, so that you can launch the runInstaller executable again.
Note. This approach assumes you have a single Oracle Home. If you have multiple versions of Oracle installed this approach may need to be adapted.
USE AT YOUR OWN RISK.
Creating Oracle ASM disks on EMC DSSD flash storage
EMC recently announced the availability of its DSSD rack scale flash storage appliance.
DSSD’s specs are impressive:
- 10 Million IOPs
- 100GB/S bandwidth
- 144TB capacity
- 100uS latency
The DSSD D5 takes a different approach to flash storage, by eliminating the latency prone networking layer typically handled by Fibre Channel, Infiniband or iSCSI. DSSD replaces this with a PCI extension through a proprietary PCIe Isley Card that connects servers to the D5.
DSSD also replaces conventional SSDs that package NAND technology and makes them look like fast spinning disks, with Flash Modules that eliminate much of the latency of mimicking spinning disks.
There’s a lot more to the D5 that just that, but I am taking a DBA centric approach, and all I want to know is, how do I consume this fast storage in my database?
PRVG-11850 : The system call “connect” failed with error “111” while executing exectask on node
During install of Oracle RAC 12c (12.1.0.2), the installer, or possibly the cluster verification utility reports an error:
PRVG-11850 : The system call "connect" failed with error "111" while executing exectask on node ...
the gruffdba 