Tape Backups and why they may run slow

Due to an interesting event earlier this week I thought it might be worthwhile doing a quick blog entry on how tape drives work and why some restores of small files can take an age to restore along with some tips on how to improve this.

Tape backup technology started out many years ago with things like the QIC and DAT. It's still used today but the tapes are more likely to be DLT, SUPER-DLT or LTO. These tapes and the corresponding drives deliver superior speed and storage capacity but the very technology that makes them high speed and high capacity can have a serious detrimental effect when backing up thousands or even millions of small files.

When you back up a file to tape it works like this:
Header:Data:Checksum

The next file is encoded in the same way so you get:

Header:Data:Checksum:Header:Data:Checksum

All fine so far. The problem occurs when you have more than a few thousand files. What happens is that the drive cannot work at it's full speed, it speeds up, overshoots the header point, slows down, reverses the tape, reads the header, maybe restores the file (if it's in the list of files to be restored) then moves onto the next one where the process is repeated all over again.

This means that a nice and shiny super fast LTO can actually run SLOWER than an older technology QIC tape drive. The QIC suffers from the same problem but due to a lesser extent because the drive technology is slower.

So what can do you to work around this issue?

What you do is the equivalent of stuffing all the files into a zip archive - Backup Exec calls this the 'intelligent image option'. All it's actually doing is dumping all the files into one big file so that it can write the file at the drives top speed without having to stop, calculate the checksum, write the checksum, write the next header, etc.

If your backup software does not support an intelligent image option or similar you can configure NTBackup to backup the data to a single .BKF file then back that file up - The drawback here is simply that a restore will take a while because you will be restoring the .BKF then extricating the actual data out of the BKF rather than selecting the file directly from the backup software.

Home Network Re-Org

I've had recent set of fun and games on my home network.

Because of some work I had happening at home I had to unplug all the kit and move the racking out of the way so that workmen could get to a set of pipes behind the server kit and check out some of the water and electrical kit. I do sometimes wonder what they think when they walk into the house and see kit that can rival a small business!!

Anyway, I know that I've been needing to remove a lot of the redundant wiring and re-label a few bits and pieces. I was actually quite horrified and the knot of cabling that was behind the servers. It's something I'm actually quite glad I've been forced to do as I've managed to remove a lot of old and redundant cabling. I'm also looking for a decent way of labling network cables as the normal type of labeling machine labels don't enjoy the conditions that a switch can put them through.

This weekend I will get the remaining boxes up and running and I also want to rebuild the VMWare server to run Windows 2003. The current server has an issue starting up the VMWare services sometimes and according to a VMware tech note it's because the server is too slow. This machine is a fairly well specced machine so I am wondering if something in the build is broken and if Windows 2003 will work any better. More to come on this soon.

Battle of the browsers - Round 2

Firefox 2.0 has been released hot on the heels of Microsoft's internet explorer 7. It will be interesting to see how big the take up of both browsers will be.

Whatever happens, Machines WILL need Internet Explorer 7 simply so they have a guarantee that security patches will continue to be made available for issues in Internet Explorer.

I've played with both IE7 and Firefox 2.0 - IE7 certainly has the biggest overall as tabbed browsing is now supported. Overall, I suppose IE7 works well enough but it still seems lacking in several areas to me. Two things in IE7 do annoy me:

1. Changing the default search engine is three mouse clicks (select it in the drop down, Click on options then onto apply) where as IE7 could just remember the users setting.

2. There is no ability to slipstream IE7 into an existing distribution. This means that you still have to build a machine THEN apply IE7. I need to have a look at unattended installs/Zero Administration for IE7 and see what's available.

Whilst I will be deploying IE7 I'm afraid my browser of choice for day to day work will be Firefox 2.0

Serious Network Outage on Orange Broadband

My broadband provider is Orange, Formally known as Wanadoo and before that Freeserve. For the most part they are ok. The service is an 8MB download, 256K upload. There are sometimes dropouts if the weather gets bad and I've seen the download speed throttle back to 6MB. Most of the time it just works.

Recently there have been a series of problems when logging on. Now I'm not being a good boy because I'm not using the supplied Speedtouch modem. Instead I'm using my own NetGear DG-834 router which while not against the rules is not exactly allowed! The good thing about this box is it will automatically retry and it reports issues in its own logs and into my Syslog server.

On Monday Orange suffered another in a line of failures. This one was serious as it took out some 60,000 customers for over 2 days. After constantly badgering both Technical Support and Customer services not only did I get this months fee wavered 'as a goodwill gesture' I was also told that the problem was the 'line to the password server' which I translated as meaning the network kit between the exchange (which is unbundled) and the RADIUS server. The obvious question is

• Why didn't they fail over?
• Why ISN'T there a fail over ability?

I'll be writing a formal complaint letter to Orange demanding a full explanation of the outage and asking for a copy of the investigation report. We shall see what they provide.

In the meantime I STRONGLY advise Orange customers who were affected by this outage to complain to Customer Services and demand a refund for the outage.

Patch Tuesday's missing patch

Last week Microsoft released 10 patches despite the advance notification saying there would be 11. Quality control issues are rumored to be at the forefront of Microsoft's decision to not deploy all eleven although they are remaining suspiciously quiet about it all.

I won't go into detail about all the patch contents here as it's all listed at http://www.microsoft.com/security

Right now the following security advisory is still outstanding:

vulnerability in DirectX animation library

rumors are around that this will be released as an out of band patch although I can't see it myself as no Proof of Concept (PoC) code exists.

Microsoft's security blog has mentioned that a PoC code exists for targeting a vulnerability in PowerPoint whether this is the recently patched security hole or a new one has not be clarified.

It's that time of the month again when Microsoft release a bumper patch collection. Tuesday will see the following released:

6 Microsoft Windows patches
4 Office patches
and a .NET framework patch.

Before these patches come out I thought it would be a good idea to go through and explain some of the terminology associated with a patch.

Patch - A patch is a SINGLE fix for a specific problem. Sometimes a patch can and will affect more than one file or more than one operating system. It is normal for these to be included in a single deployment package.

cumulative patch - A cumulative patch is a collection of patches for a SINGLE application and can be deployed without having to install all previous patches in a specific order.

Security rollup - A security rollup is a collection of patches for a variety of applications and services. A rollup can be deployed in place of the individual patches. A rollup SHOULD NOT (but has) included updates or additional fixes that are NOT available as individual patches.

Service pack - A service pack is a collection of security fixes much like the rollup but can include new fixes and NEW FUNCTIONALITY in the release. (e.g. Windows XP SP2 which included the firewall).

R2 release - A R2 release is a new thing from Microsoft. It generally arrives 2 to 3 years after a product has shipped and can include bug fixes and new functionality. it should not include any security patches. As such any further discussions of R2 releases will be for another blog!

Clear English

Ok, This is going to be a bit of a rant.

I assume that most people who read this blog work in the I.T. (Information Technology) industry and I.T. more so than any industry has its share of buzz words and acronyms. This is an accepted part of any industry or company you work in but it does end up producing a closed culture where by an outsider feels like they are intruding and now to there seems to be this incessant need to really confuse matters by using 'txt' like speak where ever possible.

This needs to STOP.

A good friend of mine demonstrated that on her phone it takes 8 key presses to spell 'later'. It also takes 8 key presses to type 'l8r' yet 'later' is the easier to read of the two.

These days it is too easy for people to slip into and hide behind technical speak for the industry that you are in but to complicate it further by wrapping 'txt' speak around it is, in my opinion, inexcusable.

I have been told that 'txt' speak is the next step in the evolution of the English language. Now, I agree that a language evolves. It has to evolve to keep pace with technological and scientific development but 'txt' speak as the next step in our language? No thank you. I am just waiting for the first computer manual or technical article to use 'txt' speak.

From here on I shall do my best to refrain from over burdening the reader with huge amounts of jargon. Where jargon is necessary I'll add in an explanation. If I forget or miss I expect the readers to call me on it!