Screwtape – Screwtape Limited

The Trails and Tribulations of Tape – A Cautionary Tale

For most of us, we have some data on some computers that we’d like to keep. For some it is critical. However, it can be a minefield, and finding a suitable strategy can be difficult.

Having spent a lot of time in the past moving precious data from one hard drive to another, and using fault tolerant RAID arrays to protect important data, I decided that it would be a good idea to invest in a long term and repeatable backup, and tape seems to be the accepted way to do this.

Since I don’t want to invest the life-savings in a state of the art tape drive, an older (but still very capable) model should do for what I need.

Hence I have bought an HP LTO5 Drive – 1.5TB per tape native, and up to 3TB compressed, which depends entirely on what you are backing up. Assume 1.5TB to be on the safe side.

The LTO6 and 7 drives hold more data per tape, but the tapes are proportionately more expensive too, so LTO5 seemed like a good compromise.

However, if you’re used to using NAS or external Hard Drive as backup, tape seems to be an altogether more complicated thing and fraught with troubles.

As I have an HP server, I decided to buy an HP drive as that should ensure it was compatible. There are good second hand offers on eBay, but I found a “new unboxed” one for a good price and bought that.

Problem 1: SAS Connections

If you’re used only to SATA (as I am), SAS is quite a new and complicated thing. I checked the specs for the server I was going to put the drive in, and it says that it has SAS connections, so that should be all right? Wrong! While there are SAS connections in the server, the are all used in the 4 non-hot-swap drive bays. Ok, says I – I’ll plug in one of the HDDs into the SATA port, and free up a SAS port. Brilliant – the HDDs are fine, and the tape drive lights up.

Does Linux recognise it? Of course it doesn’t – the hard drive controller in the (albeit entry level) HP server offers SAS connectors and says SAS on the specification (I did check before buying the drive), but is only capable of driving SATA hardware. Thanks HP!

A new SAS controller card and suitable cables (an extra £200 odd) and I’m in business – or so I thought.

Problem 2: Warranty Support for Updates

So I try a backup – looks good, and then an error…

Try again… looks good… error.

Reading about the errors I was getting on various forums, the advise seems to be to update the tape drive firmware.

However, just because the product is advertised as “new” by the seller – don’t expect HPE to give you up-to-date firmware to go with it – this is “enterprise” kit you have to pay for support if the item is out of warranty – and there is no way of finding out if it is in warranty if you don’t buy from HPE directly, or from an authorised reseller. (i.e. not from eBay)

A Solution

Noting that the problems documented as fixed by the update didn’t include mine, I continued to search websites for the specific error I was getting which was only shown by dmesg, not by tar, and found that when using tar with an LTO5 drive, the block size is essential.

The advise given here was you should use at least 256kb blocksize for an LTO5 drive.

So, almost like magic, adding the parameter “-b 512” (i.e. 512 x 512b = 256kb) to the tar command fixed the problem, and I’m now backing up to tape, but only after several hours of scouring the web and pulling my hair out.

Conclusion – the Moral of this Story

Tape backup is a whole order of magnitude more complicated and expensive than an external HDD or NAS drive. Don’t start down the road of tape unless you really need it, and can invest the time and energy in getting it to work properly.

Do your research thoroughly before buying anything, especially 2nd hand, and don’t assume just because you see something on the documentation that it will work without additional hardware and/or software.

Was it all worth it? Well, I hope I’ll never need to find out…

Page Layout Settings and Headers/Footers in EA Virtual Documents

When trying to generate a document using the virtual document generation facility in Enterprise Architect, I’ve been struggling to get the formatting to match the template for my client.

It appears when generating the virtual document, the page setup/layout parameters (i.e. margins) are derived not from the first template used in the virtual document, as I would have assumed, but from the last!

Clearly, unless you apply section breaks to the templates, each template called overwrites certain parameters (including the margins) for the overall document.

While I can understand why this might be the case, it does seem much more intuitive that these details would come from the first template in any section, rather than the last, since you would usually have a fairly specific first template for any particular document type.

I also note that the same is true for headers and footers. If you have headers and footers in a cover sheet, as they are in a separate section in the created document, the headers and footers are retained, and propagate to the whole document (assuming you don’t have other headers and footers defined).

However, if the header and footers are in the in a standard document template etc., they are overwritten by the last template in the virtual document, even if there is no header/footer defined in that there not being any header/footer defined.

The Truth is like a Maypole Dance

I have listened to many people who have claimed to have The Truth. To be honest, when I was younger, in my arrogance I thought I knew “The truth”, when others had missed it.

However, I now think truth is quite a difficult thing to pun down. The precise definition of truth is dependant on where you are now, and where you are headed.

The picture I use is a maypole dance. Accepted that this is a pagan fertility symbol, but it still has something to teach us.

Let us assume that the maypole is the absolute undisputable truth – God’s peculiar knowledge – then we are the dancers, each holding a ribbon. While we dance, we slowly get closer to the absolute truth, but never looking directly at the truth, or moving directly towards it.

We have our personal and social perspectives, that prevent us seeing the objective truth, only the subjective. However, when we continue with life’s dance, we move around and see from different perspectives, and gradually, the ribbon plaits and we get closer and closer to the absolute truth together.

However, when one of life’s dancers insists where they know the absolute truth where they are and stands still, it breaks the dance, and nobody is able to get any closer to the pole of absolute truth, and instead the ribbons start to get tangled around the person who stands still.

Just as scientist depart from science, when they claim to know anything as Truth, so all of us must retain the humility of seeing through a glass darkly, and continue to seek enlightenment. When we insist know the absolute truth now, we simply demonstrate our folly, and cause others to get tangled too.

The Advantages of a Broad Church

“What kind of Christian are you?”

I have no real idea how to answer that. I’m just not sure where to pitch myself. I used to be an evangelical. I still think of myself as being so, but I’m not sure everyone would agree.

You could describe me as Progressive, and I definitely agree a lot more closely with a lot of “Progressive” doctrines than “Conservative” evangelicals, especially those in US. I believe evolution happens, and that the world is billions of years old.

I’m a member of an Anglican church, but I’m not sure that helps to identify me.

The Anglican Church is a broad church, and that is a good thing.

It is necessary to question progressive change, with an eye to the Bible and the church’s traditions, so as to ensure that progressive ideals do not depart from Christ centred Christianity. Tradition acts as a break that prevents us moving too fast to be able to see the perhaps unintended impacts of good intentions.

However, it is equally necessary to have progressives challenging the traditional interpretation of Scripture and sacrament, as was demonstrated by Wilberforce et al., when the Abolitionists questioned the “scriptural” defence of slavery that was prevalent at the time.

It would seem like the response to people of alternate sexuality demonstrates this tension. The conservatives strongly disapprove, quoting bible verses to justify their position. The progressives say that it’s not an issue and quote different verses to justify their position. In the meantime, the church looks very foolish to those outside, and fails to carry out its mission because it spends a lot of its energy in-fighting.

The challenge to progressives, and traditionalists both, is to learn to value each other’s contribution to the Church, rather than to see the other as “the problem”. That way we can, between us, discern God’s will for to care for each other, the world, and show God’s love to everyone without discrimination.

The Serpent and the Source of Original Sin?

The concept of original sin is quite controversial in the modern world, and yet is a core part of the theological background that we have inherited.

The idea that people are inherently sinful, as a product of their birth, which when you see cute little babies, it’s hard to accept.

However, when you look at the state of the world it’s a lot easier to accept.

It is clear, that humanity has the capability to be noble, generous, kind, and altogether very positive. However, it does seem without a conscious decision towards “good behavior”, a number of negative behaviours do seem to creep in, and take over. Even St. Paul says “For what I want to do I do not do, but what I hate I do.”

Having had a conversation about the multiple layers “evolutionary” layers within our brains, it occurred to me that perhaps “original sin” is actually located within our “lizard brain” – the most primitive remnant of our brains – the “basal ganglia”, which is believed to be responsible for “species typical instinctual behaviours involved in aggression, dominance, territoriality and ritual display” (Wikipedia).

That would explain why Darwinian “survival” mechanisms seem to take over, if we either feel threatened, or abdicate our “higher” functions, such as in mob-mentality, or just when we choose to stop thinking for ourselves.

While this is wild conjecture, and I’m sure both theologians and neuroscientists would have lots to say that this is hugely oversimplifying and probably heretical, it strikes me as having a certain resonance with my own life and behaviour, and provides me a psychologically plausible explanation.

However, if this is the source of our sinful nature, then that goes to show how incredibly perceptive the writer of Genesis 3 was. Humankind is tempted into sin by the whispering of a serpent – maybe not an external serpent – but the “reptile brain” within humanity itself.

The Bible Tells Me So – A Review

I have just completed another of the exciting books I bought in order to give away, but this one I’ve read first, since I didn’t dare give it to anyone before having read it first.

“The Bible Tells Me So…” by Peter Enns.

The purpose of this book is to suggest how to read the bible without being bound to treating it either as a 21st century history textbook, or as a legal textbook.

The author goes about challenging a specific event in the Old Testament’s accounts of Israel’s history, and in so doing, challenging the 21st Century athiest’s interpretation that the God of Israel is a monster, and thus cannot be true.

Interestingly, while the author references “The God Delusion” by Richard Dawkins (which I will review in another post), there is a slightly bizarre similarity in the structure of the two books.

Another similarity I noted while reading this, was that at some points in the book, it was almost like reading “The Da Vinci Code”, and that an almighty conspiracy was being revealed. Thankfully, the writing style is a lot better…

Given all that, the book finishes what it set out to do, and the author is (given what he’s trying to do) extremely reverent for what he considers the Bible to be – a Holy Scripture – but not a factual history or a book of clear and consistent rules.

The final result of me reading this, is that the Bible has just moved up to the top my (long) list of books to read!

Kissing Fish – A Review

Someone, just before Christmas, suggested that a small group to which I belong, should all get Christmas presents for one-another. What I really needed was some extra stress finding yet more presents for people.

My wife, suggested I should buy them all books, and made some suggestions. I’m never good at giving books I haven’t read myself, so I ordered a few for my kindle and proceeded to try and read them all before giving them away. Sadly, I just don’t read fast enought for that.

Nevertheless, this is how I ended up reading a book called Kissing Fish (Christianity for those who don’t like Christianity) by Roger Wolsey.

I have personally done a lot of thinking over the last few years, and my faith has changed as a result.

This book sets out to be a systematic theology for “Progressive Christianity”, and reading it, I find that a lot of the ways in which my thinking has lead me resonates with progressive Christianity.

The author tries to be very clear as to what “many progressive Christians” believe, and offers a broad spectrum upon which many would find themselves. He then sometimes offers a personal reflection about where on the spectrum he falls.

Some of the ideas described I would consider bordering on Christian atheism, or extreme liberalism (if that’s not an oxymoron), and go beyond my personal “comfort” zone. However, it is always useful to see the ends of the spectrum when trying to places oneself upon it.

What is interesting is how centred on the teachings and acts of Jesus, and of the behaviour of the early church progressive Christianity is, given the previous paragraph, and that the focus is largely about embodying Christian values of love and grate towards everyone.

This is a fascinating book, which has helped me to see that I am not alone in a lot of my thinking. I would strongly recommend reading it if you have any concerns around the “traditional” or “evangelical” Christianity

Migrating CentOS5 VMWare images with LVM to KVM

I’ve decided that using VMWare Server has been a useful and worthwhile experience, but I want to do stuff which would involve upgrading to one of the paid-for versions of VMWare and I don’t want to pay.

So, I’ve set up a new server to host my VMs on Fedora 14, and am migrating to using KVM instead.

I had expected that I’d have to backup the image and then recover it, but no, it seems that the open source community has done everything I need. I started here and noted the slightly scary caveat that LVM using images didn’t work.

I tried anyway, and sure enough, I got a message saying

Volume group "VolGroup00" not found
Unable to access resume device (/dev/VolGroup00/LogVol01)
mount: could not find filesystem '/dev/root'

It had to be possible. I asked at LinuxQuestions.org, and the reply led me to look at virt-p2v, which was a possible fallback option, but rather scary since there aren’t any hosted pre-build iso files any more.

However, reading some of the blurb on the author’s blog about manual p2v he mentioned possibly having to edit the fstab file to point the mounts in the right direction following virtualisation.

I had loaded the converted qcow2 image, using Virtual Machine Manager. When I looked at the setup I noticed that the disk setup looked like this:

I Googled VirtIO and found that it was a para-virtualised disk type, which meant that it had to be supported by the guest OS. This would explain why the Fedora 14 rescue disk could see the LVM but not the actual operating system.

I deleted the disk entry and replaced it with this:

Now, I started the guest, and it booted!

Upon booting, the X-window display didn’t work, but the automatic rescue process worked, and I got a gnome login screen. The next problem was that the mouse didn’t work properly. The Virtual Machine Manager does suggest that you add a tablet to the machine to ensure that the mouse matches the VNC mouse, but it still didn’t work after doing that. However, yet again, someone had done the work first, and I found the answer here. Slightly messy editing the xorg.conf file, but it worked.

The Disadvantages of not Keeping Current

I have been requested by a client to produce data extracts from an old bespoke system, which has been knocking about for many years and been left without upgrades for several years. A nice piece of work for me, but it’s got me thinking about the whole upgrade lifecycle issues and bespoke vs packaged solutions in general.

The reasons it’s not been upgraded are that “it ain’t broke – don’t fix it”, and that nobody wants to pay the costs to keep regression testing new upgrades.

However, there are disadvantages to letting a system continue on old techonolgy for a long period of time. Maintenance gets more difficult as fewer people are available who remember the older technology. The world moves on and the system doesn’t, so it looks antiquated, and leads users to feel irritated by the inadequate user-interface.

The net result is that a new proprietary packaged system is going to be deployed replacing the creaking bespoke system, at considerable cost. However, as with all packaged solutions, the “out of the box” fit with the business requirement is good, but not perfect. Ok, the bespoke system doesn’t fit with the business 100% either, since the business has moved on and it hasn’t, but I can’t help thinking that had the bespoke system been periodically upgraded to use the latest (or at least more recent) technologies, and the changes to the requirements, that the requirements fit could have been better and the overall cost less than the new replacement system.

A final disadvantage of remaining on older techonolgy, comes when carrying out the extract of data for migration, you realise that “that approach doesn’t work on that version, you need the next one”. Realising that several approaches aren’t possible due to the features I’m now used to being for more recent versions, it becomes frustrating to have to rethink each time.

Decimal keypad in iPhone SDK – Well Done Apple!

A few days ago I was trying to find how to get a decimal point in the number pad for an app I was writing. Having reviewed a number of discussions on the subject which suggested subclassing the keypad or adding extra buttons and all sorts of scary things, I finally resorted to the manual.

In the list of available keypad types, it turns out that there is actually a new one in SDK 4.1. Unfortunately, at present, they haven’t updated Interface Builder with the new values, so you can’t select the new values directly but you can programatically, like this:

textField.keyboardType = UIKeyboardTypeNumberPad;

so clearly they have listened to the needs expressed in these various articles, but unfortunately, this is rather well hidden in the documentation, and until it appears in the keyboard type picklist in Interface Builder, will remain so.

So well done Apple for adding UIKeyboardTypeNumberPad, but please can you add it to Interface Builder too!