Somewhere out there!

VMWare bases the MAC address of interface on it’s internal UUID. If you shift a machine (copy, rename) vmware asks to update the UUID. You might get something like this:

# ifup eth0
SIOCSIFADDR: No such device
eth0: ERROR while getting interface flags: No such device
SIOCSIFADDR: No such device
SIOCSIFADDR: No such device
eth0: ERROR while getting interface flags: No such device
eth0: ERROR while getting interface flags: No such device

The solution found by hbraga is to check /etc/iftab. Ubuntu on install adds the MAC address for each interface to this file. Either comment out the lines or update them to reflect the correct details.

Technorati Tags: vmware, ubuntu, network error fix

AnandTech: Server Guide part 2

Even the so called “Nearline” (Seagate) or “Raid Edition” (RE, Western Digital) SATA drives which are made to operate in enterprise storage racks, and which are more reliable than desktop disks, are not made for the mission critical, random transactional applications. Their MTBF (Mean Time Between Failure) is still at least 20% lower than typical enterprise disks, and they will show the similar failure rates when used with highly random server workloads as desktop drives.Also, the current SATA drives on average experience an Unrecoverable Error every 12.5 terabytes written or read (EUR of 1 in 1014 bits). Thanks to the sophisticated drive electronics, SAS/SCSI disks experience these kinds of errors 100 (!) times less. It would seem that EUR numbers are so small that they are completely negligible, but consider the situation where one of your hard drives fails in a RAID-5 or 6 configuration. Rebuilding a RAID-5 array with five 200 GB SATA drives results in reading 0.8 terabytes and writing 0.2 terabytes, in total 1 terabytes. So you have 1/12.5 or 8% chance of getting an EUR on this SATA array. If we look at a similar SCSI enterprise array, we would get a 0.08% chance on one unrecoverable error. It is clear an 8% chance of getting data loss is a pretty bad gamble for a mission critical application.

Another good point that Seagate made in the same study concerns vibration. When a lot of disk spindles and actuators are performing a lot of very random I/O operations in a big storage rack, quite a bit of rotational vibration is the result. In the best case the actuator will have to take a bit more time to get to the right sector (higher seek time) but in the worst case the read operation has to be retried. This can only be detected by the software driver, which means that the performance of the disk will be very low. Enterprise disks can take about 50% more vibration than SATA desktop drives before 50% higher seek times kill the random disk performance.

Technorati Tags: hardware, storage

AnandTech: Server Guide Part 1

There are two big problems with the “hardware choice does not matter much” kind of reasoning. The first is that the TCA is still a big part of the total TCO. For example this study[1] estimates that the price of buying the server is still about 40-50% of the TCO, while maintenance comprises a bit more than 10% and operation costs take about 40% of TCO pie. Thus we can’t help but be wary when a vendor claims that a high price is okay, because the maintenance on his product is so much lower than the competition.Secondly, certain hardware choices have an enormous impact on the rest of the TCO picture. One example is hot-spare and hot-swappable RAID arrays which on average significantly reduce the time that a server is unreachable. This will also become clearer as we dig deeper into the different hardware features of modern servers and the choices you will have to make.

RAS features

Studies done by IBM say that about 50% of the hardware failures are related to hard disk problems and 25% are due to a power supply failure. Fans with 8% are a distant third, so it is clear you need power supplies and hard disks of high reliability, the R of RAS.

Technorati Tags: hardware, server

This is pretty clever: Running Windows on the Amazon Elastic Compute Cloud with Qemu and Linux.

Technorati Tags: ec, qemu, windows

rPath is some thing I’ve been meaning to learn about for a while. I particularly like their view on the future of software and virtualisation, which is similar to my view of software appliances.

Linux.com | Talking virtualization with rPath
Another trend that Adams expects to become clearer by the end of 2007 is a concern about how to manage virtual applications. As virtual applications come into wider use, Adams suggests, “the normal cycle of supply and demand will actually result in everyone consuming more software.” If that happens, then the question becomes, “What sort of characteristics does a virtual appliance need to be more maintainable, more manageable?”

Traditionally, software vendors have assumed that management of their products is the customers’ concerns. However, as virtualization takes hold, Adams expects to see vendors as starting to offer managed services. “One of our hypotheses about what virtual appliances can do is freeing the end user from worrying about the IT stack, operating system, and other issues, because they’re essentially black box and having the software provide all that, which shifts responsibility and control” Adams says. “Now, [if that happens] you have to ask: ‘If I were a software vendor, what would I need?'”

Manageability is one of the aspects that I think will drive the uptake of Software Appliances. Virtualisations creates the platform to allow the outsourcing of application management to those best suited to handle, while allowing the client to retain ownership of their data and enviroment.

Technorati Tags: virtualisation, software appliances, rpath

Since wordpress.com wasn’t an option due to the CNAME issues, I’ve shifted the blog to Dreamhost. I’ve got a Dreamhost account for other things, but it will serve well enough for this blog allowing me to retire one of my virtual machines.

My old theme was using some old functions which are now broken, so I’m temporarily using the default WordPress theme. However it seems to be broken for the index page. I’ve been meaning to update my theme for a while, but never find the time.  Probably have to sort it out later, seems to be a bug in the sidebar.php.

I’m thinking of moving to wordpress.com so I can ignore the monthly hassle of upgrading WordPress avoid any security issues. Particularily when I’m out of town this is a PITA.

Had an issue with nod32 not updating on one of my computers today. The c:\temp\ directory was missing. Nod32 was in silent mode and it seems that this error is not sufficiently urgent enough to warn the user. The it was refusing to download the latest dat files, probably because it was trying to unrar the update.ver file into the non-existent c:\temp\.

Technorati Tags: nod32, anti-virus, bug-fix

Also discovered Scrybe, the online/offline calendar and organizer from TechCrunch, it looks very cool. It would be interesting to know if it can sync with my Nokia E61.

Check the demo video on the Scrybe site, it has been put together very well.

Technorati Tags: calendering

From Uh Oh, Gmail Just Got Perfect:

Google quietly added a small feature to Gmail this week called Mail Fetcher. When that feature launched, Gmail became perfect.

Mail Fetcher allows users to access non-Gmail email accounts from within the Gmail interface. If you have a Yahoo email account, and a work email account, etc., you can simply access that email from within Gmail, using POP settings. Gmail will now work in a very similar way as Outlook does on the PC desktop.

Although savvy users are already ‘forward’ their mail, this feature will likely make Gmail much easier to use for the other set of users.

Technorati Tags: gmail, pop, email