Showing posts from December, 2008

EMC PowerPath, LVM and clusters

Another note on using PowerPath in Linux...

When using 2 Linux servers and PowerPath with a bunch of shared LUNs in order to build a cluster, e.g. Oracle RAC, you have to ensure that on both servers the LUNs are designated as the same /dev/emcpower* devices. Linux is a bit flaky in device enumeration and often, the order of devices gets mixed up. PowerPath can easily fix this.
Use powermt save file=devmap.pp on one host of the cluster and use powermt unmanage dev=emcpower{a,b} and powermt load file=devmap.pp on the other, to make sure they both have the same mapping. Then do a 'powermt save' to make the configuration persistent.

Also, when using LVM in conjunction with PowerPath, you don't want regular SCSI devices (local disks or perhaps iSCSI) to intervene. You can tell LVM to ignore certain devices completely when it comes to LVM. In my case I've included the filters below to make sure Linux VMs and BMs (bare metals) get the proper config. Put this in /etc/lvm/lvm.conf

Comparison: EMC PowerPath vs. GNU/Linux dm-multipath

While on the topic of Support cycles and End-of-Life (EOL) notices... EMC has given PowerPath 5.0.0 for Linux an EOL from May 31st, 2009. So I'm checking if we'll upgrade to PowerPath 5.1.x or switch over to a fresh Linux release and use dm-multipath (aka dm-mpio, native Linux multi-pathing.

blog'o thnet has a nice Comparison: EMC PowerPath vs. GNU/Linux dm-multipath for your convenience.

64-Bit Java For Linux

After 64 bit Flash from Adobe, 64 bit Wine, we now also get 64-Bit Java For Linux! This 64-bit plug-in is coming as part of Java SE 6 Update 12 Build 02, which was released last Friday. This 64-bit compatibility is for both Linux and Windows, while Sun's own Solaris operating system will pick up the 64-bit support once it has a 64-bit version of Firefox.
Yeah, everyone's catching up, finally!

Red Hat and Oracle Linux support policies and life cycle

We're using Oracle Enterprise Linux in the data center, so the Red Hat life cycles are of some importance to us. However, Oracle's support policies are more important. So I took some time to dig up the nitty gritty, which I'll summarize here for my and your convenience.

Sources: Red Hat and Oracle

Red Hat SupportRHEL4 OEL4Oracle Support

General Availability14 Feb 2005Feb 2005General Availability

End of Production 1 phase31 Mar 2009Feb 2010Premier Support Ends

End of Production 2 phase> 31 Dec 2009..

End of Production 3 phase29 Feb 2012Feb 2013Extended Support Ends

RHEL3 network won't come up in VM

Here is a useful tip from the Dell Linux-PowerEdge mailing list:

If you run RHEL3, perhaps because your software still won't support a higher release or your app was built on it, and when moving your physical servers over to VMware for better support (P2V?), you notice that the network won't come up, try removing the VLAN ID from the ifcfg file, i.e. /etc/sysconfig/network-scripts/ifcfg-eth0.

Red Hat Enterprise Linux Support Policy and Life Cycle

Got a question about the Life Cycle of certain RHEL releases. When does support end? is there Extended Support? When will support on hardware (i.e. bare metal vs VM) end?
The Red Hat Enterprise Linux Errata Support Policy has all information in this area, including End-of-Life support.

Now I'm wondering what Oracle's Linux Support statement (PDF) is and how it'll differ from this, if at all...

Oracle contributes data-integrity code to Linux kernel

Network World: "Oracle has contributed data-integrity protection code, partly developed with the hardware vendor Emulex, to the Linux kernel, the vendors announced Tuesday.

The code helps maintain 'comprehensive data integrity' as information 'moves from application to database, and from [the] Linux operating system to disk storage,' according to a statement. It also lowers the possibility that erroneous data will get written to disk.

The companies' effort is meant to help data-center administrators track and address corrupted data quickly, lowering costs and downtime"

Analyst: Red Hat 'deeply undervalued,' Oracle Linux 'has failed'

CNET News: "Red Hat has been taking a beating in the stock market recently, but in a recent research note leading analyst Mark Murphy of Piper Jaffray thinks this represents an exceptional opportunity to buy into a 'deeply undervalued' company. More interestingly, Murphy finds significant cause for Red Hat optimism based on Oracle's failed attempt to undermine Red Hat with its Unbreakable Linux product.

If Red Hat's model were fragile, the thinking goes, surely a behemoth like Oracle could make a dent in Red Hat revenues? Oracle got into the Linux game two years ago, hoping to cannibalize Red Hat's business for itself.

As Murphy points out, however, Oracle has completely failed to hurt Red Hat, calling into question the belief that Red Hat's demise is just a fork away. Novell, too, despite starting to build a decent Linux business of its own, as The VAR Guy has noted, has completely failed to touch Red Hat's rising revenue."

Red Hat Enterprise Linux 5.3 Bèta

Just received notice that Red Hat Enterprise Linux 5.3 Beta has been out since October 28th... Sjeez! Why didn't I know that sooner...?
Anyway the b├Ęta will last until January 9th, 2009, so when I get from holidays, I'll have my work cut of out for me.

RHEL 5U3 brings many, many virtualization (Xen) improvements. A new kernel (kernel-2.6.18-120.el5), rebased versions of monitoring tools (lm-sensors, net-snmp, openIPMI, openldap), new versions of yum and rpm, updated Kerberos subsystem, newer SAMBA (3.0.32) with support for Vista and Windows Server 2008, a ton kernel fixes and features, new hardware drivers (bcm43xx, bnx2/bnx2x, cpufreq, e1000/e1000e, mptscsi, qla24xx, etc.) and some interesting Technology Previews!

dm-multipath install, which should allow anaconda to install Linux on systems with 2 or more HBAs.
Support for ext4 file systems.
CIFS (aka SAMBA) enhancements in the form of kernel DFS support and Kerberos security.

Check the complete Release Notes for a full update of f…

IRQ timeout and {busy} message for cd-rom drive

I've been seeing a weird error on my server console lately. We're using Dell PowerEdge 2950 and 2950 III running Oracle's Enterprise Linux 4U5, source code from RHEL AS 4u5, with no patches applied. Straight "base distribution" (I know, I know, bad idea but bare with me). I reported it to Dell's PE mailing list, but didn't get any conclusive answers. So I'm listing it here, for reference.
Sep 1 15:36:26 kernel: hda: irq timeout: status=0xd0 { Busy }
Sep 1 15:36:26 kernel: hda: irq timeout: error=0x00
Sep 1 15:36:26 kernel: hda: ATAPI reset complete

I've found various reports of similar errors on different hardware but all seem to revolve around Red Hat's 4 release (OEL, RHEL, CentOS, Fedora) with various updates. See [1] [2]

Some sources say it's a DMA-related issue. Others suggest to turn off ACPI using kernel boot parameters acpi=off and another says it's simply the HAL daemon probing your devices. You can configure the hald to stop re…

Restricted Accounts And Vi(m) Tricks in Linux And Unix

Just want to blog this article about using Restricted Accounts And Vi(m) Tricks in Linux And Unix to increase security and limit the tricks people can do by breaking out shells and editors.

For instance, if people or processes need to be able to write in a specific location on your system, and you want to lock them down as far as you can, you could use a chroot jail together with a restricted shell to limit their options completely.