A power-cut took out the disk with my /home on it on my desktop at work (Seagate Baracuda SATA), something undetermined killed the disk in my laptop (Toshiba disk inside Powerbook), and now the disk in my home desktop has started making an interesting noise – a little like a puppy (Maxtor SCSI inside Ultra 60).
When buying disks (this is for internal use rather than resale, and we have standardised on Seagate SATA models at work), we have grown to expect (and try to cater for) a 2-ish% failure rate of new models. We actually expect a handful of disks to be DOA whenever we buy any. We don’t build any such expectations into orders of other components. This is before any disks die in service, which they tend to like to do.
Looking after desktop storage is relatively easy when you export user writable areas over a network. Raid mirroring, and decent disks go a long way to continuity of storage service. But here you’re really just masking the underlying problem – magnetic storage is terrible today. This is also no help for mobile computer users, and it seems disks inside mobile computers are most at risk.
Companies like Bitmicro are bringing drop in replacements for your typical desktop disks, that use solid state electronics instead of magnetic methods. They are slow, though. The Barracuda disk in my desktop brags sustained read speed of 150MB/s (though hdparm claims that’s closer to 80). The Bitmicro device is only capable of 28.
There is tonnes of opportunity for development in this area. If the storage can be battery backed, instead of relying on some high-end controller to take a write-cache, then great, we’re better protected from the sort of data corruption that can occur after a power failure. If transfer can get faster, then the lines between RAM and permenant storage starts to blur. Imagine if you simply had to cater for what we call swap today – this would make memory requirement planning and upgrades easy. Moreso if these next-generation disk drives are hot-swap..
But, for today, my experiences of the previous week exist to remind me – backups are really important. Take lots of them.
When I first installed OS/X 10.4, I thought that Dashboard was incredible. Now, just like Front Row, I’d much rather not be running it all the time (I found that nomatter how useful it looked, I could not ‘integrate’ it with the way that I liked to work with my computer.)
OS/X is great, but I always admit that it’s a memory hog; anything I can strip out of a running system, I do. After a reinstall (reason why this was needed coming up in a later post), I always cut out Dashboard. So as a reminder for myself how .. this is the best way.
sudo defaults write com.apple.dashboard mcx-disabled -boolean YES
killall -1 Dock
You can then remove Dashboard from the dock..
(only performed after a check that killall has the same effect as on Linux rather than Solaris!)
I still think dashboard is great, but I can’t find a use for it with the way I personally work. I am sure many Apple users feel the same way. I wonder how many Windows Vista users will feel the same way when they install the upgraded MS Operating System…
Syslog-NG is a reimplementation of the traditional syslog protocol and application in unixy operating systems. Its use to systems administrators, is to allow companies/users the chance to fully centralise their logging in one place, which makes auditing, enforcing policy, compliance measuring, and gathering marketing statistics much easier.
Some potentially non-obvious hints to help fellow admins on the way :
– When I explained that the config file was a sprawling mess to a friend, he told me to think of it as a config style for a simple router. Messages are delivered, and match given conditions (a source, and optionally a filter). You can then bend these messages across different interfaces (or, logfiles). One ‘complete’ configuration needs to be made up from at least one message matching rule, and one logfile, so might look like this :
filter f_myapplication { facility(local3); };
destination l_myapplication { file (“/var/log/application.log”); };
log { source (s_all); filter (f_application); destination (l_myapplication); };
– understand just how important the ‘flags’ rule is. I started logging one of our application logs without really realising what the effect of what catchall rules were doing. I found I was logging application notes in /var/log/hosts/hostname.log, /var/log/messages, and the application log :
log { source(s_all); destination(hosts); };
is a good catch all because it will almost certainly catch any log and file it in a sensible place (e.g. today’s notes from x host) – but when you are generating hundreds of GB of logs every day from your network, such a scattering of identical logs, is a bad situation. I now have application specific logs at the top of my file and specify a flags(final); in the ‘log’ line – this means ‘stop here’. It probably follows that the most regularly hit log lines need to be at the top of the list for performance enhancements.
– syslog-ng can completely obliterate the requirement for log rotation. This is definitely exciting, as even if you are running syslog-ng locally, instead of spooling log notes across your managemenet lan. Rotation is a pain, your night-time scripts which do the rotation, and then send cluster-bombs of hangup signals might go wrong, catch-all configuration in tools such as logrotate need to be understood by everyone, and you may find you need to do your logfile compression at a different time of day to your rotation, which just creates extra scripting jobs.
Logging straight into the ‘rotated’ or archive position makes much more sense. A destination directive such as :
destination l_redline { file (“/var/log/application-combined/$R_YEAR/$R_MONTH/$R_YEAR-$R_MONTH-$R_DAY-application.log”); };
means an end to the overnight logrotate hour and compression – you can compress on an ad-hoc basis so that the maximum amount of uncompressed logs are available to you if you wish, and you always know that the logfiles will rotate at exactly the right moment, when the day changes (which is right in most of this company’s contexts..)