Sun, 24 Apr 2005
Linux FireWire Clustering: Brain Dump
I had an interest in shared storage FireWire clustering on Linux for a
while. After spending a couple of evenings learning about it and having a
little play I ended up with a big text file of links and notes. Below is
the slightly more rationalised version of my notes. If I ever need it again
I'll try and write them up properly, in the mean time they might serve as a
useful pointer to some other traveller.
Thanks to a push by Apple FireWire is now reaching commodity status. The hardware itself is getting cheaper and widely available. Software and operating system support is getting better and as these continue to increase more people will hack around with the technology. I've only become interested in FireWire for one main reason; as cheap, shared storage.
It's been possible to share SCSI disks between two or more machines for quite a while. Unfortunately the hardware required has always been expensive, uncommon and (at the lower end) had a lot of problems with one machine rebooting and causing problems for all the others. So why do people use it? Because it's one of the best ways to do multi-node shared storage.
If we look at pure performance then FireWire isn't going to upset the SCSI or fibre channel users too much, while it's quick enough for basic networking (Apples IP over FireWire) it's not really suited for a heavily used production environment; but if you have one of those then you should invest in a SCSI or fibre channel based option instead. So why would you use FireWire for shared storage?
There are two main reasons, firstly (and these articles whetted my interest in shared FireWire) Oracle have documented how to use FireWire Real Application Clusters and even their Director of Linux Engineering, Wim Coekaerts, has written about Setting Up Linux with FireWire-Based Shared Storage for Oracle9i RAC as an economical way to develop and test RAC environments without requiring two hideously expensive storage deployments; one for live and one for dev/QA. It's worth noting that while Oracle do mention this as an option they don't in any way (at the time of writing) support it. It's going to be a long while before you see FireWire shared storage holding Oracle databases in live!
So how do you do it? A number of external FireWire drives (the Oxford 911 chipset seems to work well) allow multiple simultaneous logins to the device. If you have two machines with decent FireWire cards (I don't have a list of which ones do and don't work) and (this is VERY IMPORTANT!) a decent clustered file system (OCFS is known to work and GFS may be usable) then you can configure hosts running Linux to share the storage. For full details have a look at the Oracle articles above.
As an aside under Linux you can use software called DRDB for sharing storage across two machines. Here's a summary taken from the DRDB site itself "DRBD is a block device which is designed to build high availability clusters. This is done by mirroring a whole block device via (a dedicated) network. You could see it as a network raid-1. DRBD takes over the data, writes it to the local disk and sends it to the other host. On the other host, it takes it to the disk there." While DRDB isn't the ideal solution for everyone (for some discussion on this have a look at the Linux Clustering thread.
Notes:
- VMWare lets you pretend to have shared SCSI disks. Virtual PC server might also let you.
- When ever I found a mention of FireWire Clustering on Windows it got shot down very quickly. I don't see it being a Windows feature for a fair while.
- From IEEE 1394 and RFC 2734; a viable HSI for hypercubes: "Currently, you can get 100Mbps solid using the eth1394 driver and 120Mbps to 130Mbps using ip1394 for certain packet sizes"
- Linux FireWire Support
PS While researching FireWire Clustering I discovered how much I HATE the Google Groups interface.
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Posted: 2005/04/24 20:20 | /geekstuff | Permanent link to this entry | This entry and same date
Little Red Book of Selling -- Short Review
I always feel both a little guilty and odd when discussing books about
sales people and selling. While you need money to survive in any
business the IT people are normally quite removed from the processes of
bringing it in (technical pre-sales is one notable exception). Like most
techs I'm not a natural sales person, add to this my intense dislike of
pushy sales reps, both in my personal shopping and professionally (cold
call me on the phone and I'll NEVER buy your product) and I'm probably not
the ideal audience for this kind of book.
The Little Red Book of Selling is part good advice, part common sense and part pure ego. The author comes across as a very dedicated, driven salesman who focuses more on the long term relationship than the short term sale. Large parts of the (pleasantly small) book cover the essentials such as preparation, why selling based on price is a bad move and other little nuggets of what should be common sense.
Although the text also has (what I've always considered) a slightly American slant with more than the occasional paragraph on positive thinking and motivation the author is refreshingly blunt and honest about where the blame sits when you're unable to sell.
Amusingly the most successful bit of selling advice I picked up from this book was principle 3, "Personal Branding." I now fully appreciate how important this is, the entire book is an excellent example of shameless self-promotion that actually does work both in raising your opinion of a man you've probably never met while still being informative enough to warrant finishing. Summary: 6/10.
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Posted: 2005/04/24 15:00 | /books | Permanent link to this entry | This entry and same date
The Tipping Point -- Short Review
I enjoyed the entertaining, if not exactly revolutionary, Blink and went
looking for anything else by the same author. The Tipping Point is very
similar in style and outcome to Blink; it delves in to an interesting
subject in an entertaining way but leaves you feeling a little empty.
The book itself is well written and has a pretty wide appeal, the subjects examined and ideas presented cover such a wide range of examples that there is something in it for almost everyone. The basic premise is that there is a "Tipping Point" where interesting things happen, whether it's moving a product from niche to mainstream using intelligent marketing, treating HIV infection or the prevention of crime in New York certain aspects and people can convert a flash of something in to an epidemic.
The author explains how he sees this happening and shows a number of examples that help reinforce his ideas. While there are a couple of "Yeah, and?" moments there are also some "So that's how it..." which makes it a decent enough read for the price of the paperback. What made it an interesting read for me is that with a greater understanding of some of the principles presented some of the online projects and communities I'm involved in should be able to kick start some more growth, and anything that helps us do that is worth some investigation. Summary: 6/10.
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Posted: 2005/04/24 13:41 | /books | Permanent link to this entry | This entry and same date
Mobile Computing
I've been out of touch with most of the world (and reality) for most of the last
seven days due to personal and professional demands on my (ever so badly
managed time). The one thing I've concluded is that I need a new, light,
laptop and a source code control system that has a sensible off-line mode.
The ability to use SSH and the web over my Treo would be a bonus. I've been
looking at some older Sony Vaios (very small) and the quite new and shiny
Fujitsu-Siemens Lifebooks and I'll do some digging over the next couple of
months to work out which looks most promising (and in my budget!); but it
won't be a mac. I don't like them that much.
Update: A quote from my review of Painless Project Management with FogBugz has been used on the Apress Project Management with FogBugz page!
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Posted: 2005/04/24 11:19 | /meta | Permanent link to this entry | This entry and same date
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