sabi notes
http://WWW.sabi.co.UK/
Notes mostly about Linux and computer issuesen-GBhttp://blogs.law.Harvard.edu/tech/rss/notes {at} notes.for.sabi.co.UKCopyright 2007 Peter G.14000AMDIntelMicrosoftNintendoSonyCPUOSVoIPfile sytemfree softwarehardwareperformancesystem administrationvideogamesvirtual memoryALSADebianFedoraGNUJFSKDELinuxMS Windows 2000MS Windows XPMS WindowsPS/3RedHatSUSEUNIXXFSXbox 360ext3Tue, 26 Feb 2008 21:30:00 +0000Much better read latency with AMD's HyperTransport
http://WWW.sabi.co.UK/blog/0712dec.html?071210#071210
AMD CPUs have much better read latency than Intel
ones thanks to HyperTransport. But memory sticks are designed to
have high latency as Intel CPUs have lots of onchip cache
anyhow.architecturehardwareAMDIntelhttp://www.sabi.co.uk/blog/0712dec.html?071210#071210Mon, 10 Dec 2007 21:30:00 +0000Slow remote X display with Exceed and antialiases fonts
http://WWW.sabi.co.UK/blog/0706jun.html?070609#070609
Peculiar case where a remote X display using
anti-aliased fonts is abnormally slowsystem administrationX11fontshttp://www.sabi.co.uk/blog/0706jun.html?070609#070609Sat, 09 Jun 2007 22:00:00 +0000Software versus hardware RAID: bandwidth, latency, convenience
http://WWW.sabi.co.UK/blog/0706jun.html?070602#070602
Software RAID has a very different profile from
hardware RAID, both as to performance and administrationRAIDsystem administrationstoragehttp://www.sabi.co.uk/blog/0706jun.html?070602#070602Sat, 02 Jun 2007 22:00:00 +0000Slow transfer rate over SSH and improvements
http://WWW.sabi.co.UK/blog/0802feb.html?080205#080205
Why WinSCP by default is slow, and general
performance issues of bulk data transfer over SSH and
solutions or palliativesperformancenetworkingLinuxMS Windowshttp://www.sabi.co.uk/blog/0802feb.html?080205#080205Tue, 05 Feb 2008 21:40:00 +0000Number of NFS server instances
http://WWW.sabi.co.UK/blog/0801jan.html?080122#080122
The number of NFS instances can be a surprising
bottleneck, and in the past it exposed a disjointed hardware
vs. software design on Sun servers.Linuxperformancenetworkingsystem administrationhttp://www.sabi.co.uk/blog/0801jan.html?080122#080122Fri, 22 Jan 2008 21:05:00 +0000BCM5752 jumbo frames work only in output
http://WWW.sabi.co.UK/blog/0712dec.html?071223#071223
Discovered that a popular 1gb/s chipset can
transmit but not receive jumbo frames, and how to take
advantage of jumbo frames at least for transmitting.hardwarenetworkingperformanceLinuxhttp://www.sabi.co.uk/blog/0712dec.html?071223#071223Sun, 23 Dec 2007 14:50:00 +0000Network accelerators run Linux
http://WWW.sabi.co.UK/blog/0712dec.html?071215#071215b
Two network accelerators recently announced,
both offloading network processing to onboard Linux.hardwarenetworkingLinuxhttp://www.sabi.co.uk/blog/0712dec.html?071215#071215bSat, 15 Dec 2007 15:10:00 +00002.5" hard disks differences
http://WWW.sabi.co.UK/blog/0712dec.html?071215#071215
A group test of 2.5" hard discs reported significant
performance differences among supposedly very similar commodity
products.hardwarestorageperformancehttp://www.sabi.co.uk/blog/0712dec.html?071215#071215Sat, 15 Dec 2007 16:25:00 +000050 times faster or infinitely scalable?
http://WWW.sabi.co.UK/blog/0710oct.html?071010#071010
Amazon's CTO would rather have a technology
that be hugely scalable than just 50 times faster, and that
to me is not that good an idea, as business is about making
money with what you have, not with the hockey stick that you
won't have tomorrow.architecturebusinesssoftwarehttp://www.sabi.co.uk/blog/0710oct.html?071010#071010Wed, 10 Oct 2007 21:50:00 +0100Selling out: upgrading to 2GB RAM and dual monitors
http://WWW.sabi.co.UK/blog/0710oct.html?071006#071006
So I have sold out and upgraded my PC to 2GB and
to avoid the consequences of poor memory management by
contemporary OSes and applications. This has been triggered
by the purchase of second monitor, allowing me to keep more
application instances around.hardwareperformancestoragememoryhttp://www.sabi.co.uk/blog/0710oct.html?071006#071006Sat, 06 Oct 2007 22:15:00 +0000SELinux brittleness and layering wizards
http://WWW.sabi.co.UK/blog/0709sep.html?070928#070928
Well reasonable points about how complex SELinux
is and how it would be better to fix that instead of providing
simple minded wizards in a vain attempt to hide that
complexity.software engineeringsystem administrationsecurityLinuxMicrosofthttp://www.sabi.co.uk/blog/0709sep.html?070928#070928Fri, 28 Sep 2007 21:20:00 +0100So the cases where RAID5 makes sense are...
http://WWW.sabi.co.UK/blog/0709sep.html?070923#070923b
Probably RAID5 makes some sense only in two
narrow cases (2+1 array and 4+1 online archive cache array)
and only to save a bit of money from RAID10.RAIDperformancestoragehttp://www.sabi.co.uk/blog/0709sep.html?070923#070923bSun, 23 Sep 2007 14:10:00 +0100Yet another RAID5 perversity
http://WWW.sabi.co.UK/blog/0709sep.html?070923#070923
because of budget constraints a 48 drive array
is deployed as 3x15 RAID5 setups. No surprise that write
performance is not awesome, and some doubts about the
wisdom of doing yet another RAID5 perversity.system administrationRAIDLinuxhttp://www.sabi.co.uk/blog/0709sep.html?070923#070923Sun, 23 Sep 2007 12:35:00 +0100More Cell and Niagara style chips planned
http://WWW.sabi.co.UK/blog/0709sep.html?070920#070920
AMD/ATi and Intel plan many-CPU chips to
accelerate scientific computations, and it looks like that the
Cell is going to have several imitators.CPUhardwareparallelismhttp://www.sabi.co.uk/blog/0709sep.html?070920#070920Thu, 20 Sep 2007 18:10:00 +0100The high CPU cost of the Linux page cache, more numbers
http://WWW.sabi.co.UK/blog/0709sep.html?070919#070919
The CPU overhead of reading from a fast disk
with O_DIRECT is several times smaller than without, because
the Linux page cache seems extraordinarly expensive. But then
high end CPUs are getting every faster.LinuxperformanceCPUstoragehttp://www.sabi.co.uk/blog/0709sep.html?070919#070919Wed, 19 Sep 2007 19:05:00 +0100AMD's 3 CPU chip
http://WWW.sabi.co.UK/blog/0709sep.html?070918#070918b
AMD have recently launched 4-CPU chips,
and now 3-CPU ones. Clever move to improve yields on their
single die chips.hardwareCPUAMDIntelhttp://www.sabi.co.uk/blog/0709sep.html?070918#070918bTue, 18 Sep 2007 22:55:00 +0100Sun's 8 CPU, 32/64 thread new chip
http://WWW.sabi.co.UK/blog/0709sep.html?070918#070918
Sun has just launched a revised version of its
highly threaded Niagara CPU chips. it is ever more designed for
naturally parallel workloads, and freshly written applications,
for which is it well suited, and it seems to perform terribly on
general purpose applications and dusty decks. In the meantime
for the latter Sun is selling a lot of AMD64 systems.hardwareperformanceCPUAMDparallelismthreadshttp://www.sabi.co.uk/blog/0709sep.html?070918#070918Tue, 18 Sep 2007 22:10:00 +0100Another used file system test
http://WWW.sabi.co.UK/blog/0709sep.html?070914#070914
Upgrading from Fedora 5 to 7, measuring again the
difference between a freshly loaded and a well used and updates
root filesystem on JFS.Linuxfile systemsperformanceJFShttp://www.sabi.co.uk/blog/0709sep.html?070914#070914Fri, 14 Sep 2007 21:35:00 +0100The .desktop file format
http://WWW.sabi.co.UK/blog/0708aug.html?070830#070830
Why .ini file style syntax is not good for UNIX style
systems and one alternative using .desktop files as examples.UNIXstyleprogramminghttp://www.sabi.co.uk/blog/0708aug.html?070830#070830Thu, 30 Aug 2007 20:10:00 +0100Translucency in KDE 3.5
http://WWW.sabi.co.UK/blog/0708aug.html?070819#070819b
KDE 3.5 translucency works, and has some advantages,
but also some significant disadvantags.NVIDIALinuxX11KDEGUIhttp://www.sabi.co.uk/blog/0708aug.html?070819#070819bSun, 19 Aug 2007 13:20:00 +0100Another advantage of eSATA
http://WWW.sabi.co.UK/blog/0708aug.html?070819#070819
As someone noticed, eSATA ahs another advantage over
USB2 or FireWire, which is power management.hardwareSATAeSATAUSB2FireWirehttp://www.sabi.co.uk/blog/0708aug.html?070819#070819Sun, 19 Aug 2007 12:35:00 +0100The Linux CPU governors don't look at system CPU time
http://WWW.sabi.co.UK/blog/0707jul.html?070705#070705
Because of various reasons my backups were running
with high system CPU time, but the CPU frequency governor
was keeping it at the lower frequency. Looks like it does not
take into account system CPU time. Anyhow I figured out that
it is nowadays better to just use O_DIRECT for backups.
Linuxstoragesystem administrationperformancehttp://www.sabi.co.uk/blog/0707jul.html?070705#070705Thu, 05 Jul 2007 21:20:00 +0100Flushing unmodified cached pages under Linux
http://WWW.sabi.co.UK/blog/0707jul.html?070704#070704
Just discovered a relatively but not so recent
way to uncache data pages under Linux other than unmounting.
Linuxperformancestoragesystem administrationhttp://www.sabi.co.uk/blog/0707jul.html?070704#070704Wed, 04 Jul 2007 21:45:00 +0100Disappointing Linux NFSv3 writing misfeature and workaround
http://WWW.sabi.co.UK/blog/0707jul.html?070701#070701b
The Linux NFS client and NFS server codes do not
implement NFSv3 delayed writing well, and 'sync' performance
suffers, but a fairly reasonable workaround can be
appliedLinuxstoragefile sysytemNFSsystem administrationnetwork administrationperformancehttp://www.sabi.co.uk/blog/0707jul.html?070701#070701bSun, 01 Jul 2007 20:20:00 +0100Outrageous Linux memory management misfeatures
http://WWW.sabi.co.UK/blog/0707jul.html?070701#070701
Not only the semantics of the 'dirty_ratio'
and 'dirty_background_ratio' Linux kernel parameters are
questionable, their implementation seems to me rather
misguided.Linuxstoragefile sysytemsystem administrationperformancehttp://www.sabi.co.uk/blog/0707jul.html?070701#070701Sun, 01 Jul 2007 17:20:00 +0100Updates to Linux help channel suggestions
http://WWW.sabi.co.UK/Notes/linuxHelpAsk.html?070528
Some improvements and updates to my notes on how to
ask question in Linux help channels, a bit motivated by seeing
my notes mentioned in the #Ubuntu '/topic' as "seriously
good".LinuxIRChttp://www.sabi.co.uk/Notes/linuxHelpAsk.html?070528Mon, 28 May 2007 15:35:00 +0100A poor UNIX legacy: dotfiles in the home directory
http://WWW.sabi.co.UK/blog/0705may.html?070528#070528
Not everything from the UNIX design is good, in
particular hidden dotfiles and configuration files hidden in
home directories are a poor idea.UNIXsystem administrationarchitecturefilesystemhttp://www.sabi.co.uk/blog/0705may.html?070528#070528Mon, 28 May 2007 13:20:00 +0100Thinking again about simplicity: laptop versus desktop
http://WWW.sabi.co.UK/blog/0705may.html?070527#070527f
A laptop is simpler to deploy, a desktop to upgrade
and repair. Simplicity is of course a relative term.hardwaresystem administrationhttp://www.sabi.co.uk/blog/0705may.html?070527#070527fSun, 27 May 2007 20:20:00 +0100The problems with Wiki documents
http://WWW.sabi.co.UK/blog/0705may.html?070527#070527e
Compared with HTML Wiki syntax seems simpler, or at
least less intimidating. But Wiki text has a number of
significant disadvantages, and the single greatest advantage is
just that the web server is maintained by someone else.documentationsystem administrationwebHTMLhttp://www.sabi.co.uk/blog/0705may.html?070527#070527eSun, 27 May 2007 19:35:00 +0100Selling advanced switching features and split trunking
http://WWW.sabi.co.UK/blog/0705may.html?070527#070527d
Having attended a sales presentation about a rather
subtle networking technique called split trunking I am
skeptical: it relies on excessive sophistication in a fully
bridged network, and I prefer simple well tested techniques,
and routing in general.ethernetnetworkingnetwork administrationhttp://www.sabi.co.uk/blog/0705may.html?070527#070527dSun, 27 May 2007 19:05:00 +0100Wildcard domain names update and spam avoidance scheme
http://WWW.sabi.co.UK/blog/0705may.html?070527#070527c
Just noticed a clarification of the way wildcard
domain names work, and this is an occasion to describe my spam
avoidance scheme which relies on wildcard MX RRs.system administrationnetwork administrationnetworkingDNShttp://www.sabi.co.uk/blog/0705may.html?070527#070527cSun, 27 May 2007 18:15:00 +0100When bridging or RAID5 are appropriate
http://WWW.sabi.co.UK/blog/0705may.html?070527#070527b
There are some narrow cases where a fully bridge
network or RAID5 storage are appropriate, like port
multiplication or mostly read-only storage caches.system administrationnetwork administrationRAIDstoragenetworkingEthernethttp://www.sabi.co.uk/blog/0705may.html?070527#070527bSun, 27 May 2007 18:10:00 +0100RAID5 and bridging/VLANs are not free lunches
http://WWW.sabi.co.UK/blog/0705may.html?070527#070527
Both RAID5 and bridged networks are based on the
assumption that difficult choices do not need to be made, and
free lunches are possible with either: one can have both
reliability and low cost without impacting performance with
RAID5, and one can have massive flexible internetworks without
routing with bridging.system administrationnetwork administrationRAIDnetworkingstorageEthernethttp://www.sabi.co.uk/blog/0705may.html?070527#070527Sun, 27 May 2007 18:10:00 +0100Non uniform LCD monitor colour temperature
http://WWW.sabi.co.UK/blog/0705may.html?070520#070520b
Having two similar but different LCDs side by side I
have noticed that the colour temperature varies with the vertical
angle of vision, and the other way round in the two.hardwaregraphicshttp://www.sabi.co.uk/blog/0705may.html?070520#070520bSun, 20 May 2007 21:15:00 +0100Another RAID perversity
http://WWW.sabi.co.UK/blog/0705may.html?070520#070520
An amusing anedocte where the storage for an
NFS server gets configured as RAID500.system administrationRAIDLinuxhttp://www.sabi.co.uk/blog/0705may.html?070520#070520Sun, 20 May 2007 21:00:00 +0100The missing links
http://WWW.sabi.co.UK/blog/0705may.html?070513#070513b
The business model of online sites is often based on
stickiness, which rewards incoming but not outgoing links, thus
ensuring that large parts of the WWW are text instead of
hypertext. Search engines then provide the missing links, too bad
for Google that it uses a link based indexing
algorithm.businesswebsearch engineshttp://www.sabi.co.uk/blog/0705may.html?070513#070513bSun, 13 May 2007 13:05:00 +0000PS3 very suitable for Folding@Home
http://WWW.sabi.co.UK/blog/0705may.html?070513#070513
The Sony PS3 is reported as being very good for
protein folding. No surprises, it is an embarrasingly parallel
problem and the Cell SPEs are well suited.PS3performanceparallelismoptimizationhttp://www.sabi.co.uk/blog/0705may.html?070513#070513Sun, 13 May 2007 11:30:00 +0000On how to keep a job as a game programmer
http://WWW.sabi.co.UK/blog/0705may.html?070506#070506c
Some advice column deludes games programmers that
constant retraining in their own time is the key to getting
increasingly scarce programmer jobs.videogamesprogrammingbusinessemploymenthttp://www.sabi.co.uk/blog/0705may.html?070506#070506cSun, 06 May 2007 21:30:00 +0000Virtual machines as failures of existing kernels
http://WWW.sabi.co.UK/blog/0705may.html?070506#070506b
Virtual machines are a good idea for sharing
the same system among completely different platforms, but
the operating system kernel should be able to do most of
the other common uses of virtual machine.operating systemsprogrammingsystem administrationhttp://www.sabi.co.uk/blog/0705may.html?070506#070506bSun, 06 May 2007 20:05:00 +0000One of the first towns to get IPv6
http://WWW.sabi.co.UK/blog/0705may.html?070506#070506
A small USA town has switched to IPv6.networkingIPv6http://www.sabi.co.uk/blog/0705may.html?070506#070506Sun, 06 May 2007 19:10:00 +0000A recent RAID host adapter does RAID3
http://WWW.sabi.co.UK/blog/0705may.html?070505#070505b
Some recent host adapter does 2+1 or 4+1
RAID3 (actually probably RAID4). Quite interesting as it is no
longer that commonly used.storagehard discssystem administrationRAIDhttp://www.sabi.co.uk/blog/0705may.html?070505#070505bSat, 05 May 2007 16:55:00 +0000Copying a 500GB disk over eSATA
http://WWW.sabi.co.UK/blog/0705may.html?070505#070505
Duplicating a 500GB from SATA to eSATA runs at an
average of 47MB/s from outer to inner cylinders (thus not peak),
which is quite impressive.storagehard discssystem administrationhttp://www.sabi.co.uk/blog/0705may.html?070505#070505Sat, 05 May 2007 16:15:00 +0000DVD-RAM, packet writing and shoddiness
http://WWW.sabi.co.UK/blog/0704apr.html?070429#070429b
Just tried some exotic dual sided 8cm DVD-RAM disc
and it even all worked writing to it, but slowly. Anyhow usual
shoddiness with poor error reporting and design in one of the
utilities involved.storagesystem administrationDVDhttp://www.sabi.co.uk/blog/0704apr.html?070429#070429bSun, 29 Apr 2007 13:20:00 +0000Promise eSATA not quite hotplug under Linux
http://WWW.sabi.co.UK/blog/0704apr.html?070429#070429
eSATA host adapters usually can do hotplug (at least
recent ones, electrically) but the current Linux drivers require
module unload and reload, which is a bit disappointing.storageLinuxsystem administrationhttp://www.sabi.co.uk/blog/0704apr.html?070429#070429Sun, 29 Apr 2007 13:05:00 +0000Fedora requires the root filesystem to be called "/"
http://WWW.sabi.co.UK/blog/0704apr.html?070426#070426c
Because it is hard coded in the default kernel 'initrd',
Fedora 5 will not boot if the root filesystem has a label other
than "/", and that is just as Microsoft would do it.LinuxRedHatFedorasystem administrationhttp://www.sabi.co.uk/blog/0704apr.html?070426#070426cThu, 26 Apr 2007 13:55:00 +0000Best way to change MS Windows boot drive letter is via registry
http://WWW.sabi.co.UK/blog/0704apr.html?070426#070426b
Boot drive letter assignments are better changed or
restored just using the registry editor.MS windowssystem administrationhttp://www.sabi.co.uk/blog/0704apr.html?070426#070426bThu, 26 Apr 2007 13:35:00 +0000Vibrations cause hard disk to die or to run twice as slow
http://WWW.sabi.co.UK/blog/0704apr.html?070426#070426
A smart person has figured out that hard disc early
deaths or poor performance were caused by vibrations transmitted
via the SATA cable or the case.hardwaresystem administrationhard discshttp://www.sabi.co.uk/blog/0704apr.html?070426#070426Thu, 26 Apr 2007 13:20:00 +0000Laptop monitor by default causes extra power draw
http://WWW.sabi.co.UK/blog/0704apr.html?070424#070424
Ironically the KDE battery monitor application
wastes battery power, easy to alleviate.system administrationKDELinuxFedorahttp://www.sabi.co.uk/blog/0704apr.html?070424#070424Sun, 24 Apr 2007 19:20:00 +0000External SATA delivers, positional device naming dead
http://WWW.sabi.co.UK/blog/0704apr.html?070419#070419
A quick test of an eSATA drive returns impressive
performance. But because of unspecified ordering of devices
which drive appears as which device file is not that fixed.
This is not going to change, and unique ids are the only
answerstoragesystem administrationLinuxhttp://www.sabi.co.uk/blog/0704apr.html?070419#070419Thu, 19 Apr 2007 20:35:00 +00003com is nearly out of the Ethernet card market
http://WWW.sabi.co.UK/blog/0704apr.html?070410#070410c
I just noticed that 3com is no longer selling
Ethernet cards, only WiFi and SSL/Firewall cards.networkingEthernethttp://www.sabi.co.uk/blog/0704apr.html?070410#070410cTue, 09 Apr 2007 20:25:00 +0000Optical fibre network cards, availability and prices
http://WWW.sabi.co.UK/blog/0704apr.html?070410#070410b
It is not easy to buy long reach optical Ethernet
cards, and for 10gb/s many products are not available.Ethernetnetworkingfibrefiberhttp://www.sabi.co.uk/blog/0704apr.html?070410#070410bTue, 09 Apr 2007 19:40:00 +0000Some disk reliability studies
http://WWW.sabi.co.UK/blog/0704apr.html?070410#070410
Two interesting disk reliability sites at
large site return interesting statistics.system administrationstoragehardwarehard driveshttp://www.sabi.co.uk/blog/0704apr.html?070410#070410Tue, 09 Apr 2007 19:15:00 +0000eSATA is out, good for servers too, FireWire 800 not yet dead
http://WWW.sabi.co.UK/blog/0704apr.html?070407#070407
The first eSATA products have arrived, and one can
buy cheap cards with 4 external SATA ports. One can then build
servers with external drives like in the old SCSI days, and they
are hotpluggable too. One could with Firewire 800 too, but eSATA
just uses standard drives.storagehardwareFirewirehttp://www.sabi.co.uk/blog/0704apr.html?070407#070407Sat, 07 Apr 2007 10:30:00 +0000Fontconfig on Fedora 6 and snappy application startup times
http://WWW.sabi.co.UK/blog/0704apr.html?070406#070406
A small bug in the font table cache utility in Fedora 6
results in the cache not being setup and rather slow application
startup times. Using the equivalent package from the the Fedora 7
development repository fixes it.LinuxfontsFedorasystem administrationhttp://www.sabi.co.uk/blog/0704apr.html?070406#070406Fri, 06 Apr 2007 11:20:00 +0000Simplicity by deliberate design and ancient texts
http://WWW.sabi.co.UK/blog/0704apr.html?070401#070401
Simplicity is not a goal in itself, but a consequence
of recognizing that unnecessary complexity leads to lower
understanding, which impacts maintainability.softwarenetworkingprogramminghttp://www.sabi.co.uk/blog/0704apr.html?070401#070401Sun, 01 Apr 2007 16:30:00 +0000Flash storage with widely different transfer rates
http://WWW.sabi.co.UK/blog/0703mar.html?070331#070331d
A recent group test of flash storage devices shows
that there is a wide variation in performance among them, and
that the slowest are devices in the xD format. storageperformancehardwarehttp://www.sabi.co.uk/blog/0703mar.html?070331#070331dSat, 31 Mar 2007 21:30:00 +0000Check of a 5TB filesystem takes 12 hours
http://WWW.sabi.co.UK/blog/0703mar.html?070331#070331c
Another report on the speed of filesystem checking
is that a 5TB XFS filesystem with many inodes took 12 hours
to check, which seems quite fast to me.file systemperformancesystem administrationXFShttp://www.sabi.co.uk/blog/0703mar.html?070331#070331cSat, 31 Mar 2007 19:55:00 +0000Simplicity, APIs, networking
http://WWW.sabi.co.UK/blog/0703mar.html?070331#070331b
programingsoftwarenetworkingarchitecturehttp://www.sabi.co.uk/blog/0703mar.html?070331#070331bSat, 31 Mar 2007 18:15:00 +0000Google and lack of non USA search engines
http://WWW.sabi.co.UK/blog/0703mar.html?070331#070331
All the major search engines are USA based
and owned. The governments of France and Germany are
sponsoring the Quaero and Theseus search projects, but
where is the beta?internetresearchhttp://www.sabi.co.uk/blog/0703mar.html?070331#070331Sat, 31 Mar 2007 15:10:00 +0000Bridged internetworking and Ethernet's past
http://WWW.sabi.co.UK/blog/0703mar.html?070304#070304
Some more comments on the problems with bridged
Ethernet composite networks.Ethernetnetworkingnetwork administrationhttp://www.sabi.co.uk/blog/0703mar.html?070304#070304Sun, 04 Mar 2007 18:10:00 +0000Another MS Windows locked file utility
http://WWW.sabi.co.UK/Notes/windowsNotes.html#wholockme
A better MS Windows locked file resolution
utility.MS Windowssystem administrationutilityhttp://www.sabi.co.uk/Notes/windowsNotes.html#wholockme?070304Sun, 04 Mar 2007 16:50:00 +0000Deleting default multicast routes
http://WWW.sabi.co.UK/Notes/windowsNotes.html#mcastRoutes
Default multicast routes in MS Windows cannot be
deleted directly, they must be first re-added.MS Windowsnetworkingmulticasthttp://www.sabi.co.uk/Notes/windowsNotes.html#mcastRoutes?070228Wed, 28 Feb 2007 20:00:00 +0000Ethernet speed and power draw
http://WWW.sabi.co.UK/blog/0702feb.html?070225#070225d
Higher speed Ethernet requires more power, and for
10gb/s Ethernet that can mean 20-30W per port, and with
star networks there must be two ports per link... power drawnetworkinghttp://www.sabi.co.uk/blog/0702feb.html?070225#070225dSun, 25 Feb 2007 19:10:00 +0000DMZ using static ARP entries
http://WWW.sabi.co.UK/blog/0702feb.html?070225#070225c
Using static ARP entries can be a fairly good idea
for nodes in a DMZ network.securitynetworkingfirewallssystem administrationhttp://www.sabi.co.uk/blog/0702feb.html?070225#070225cSun, 25 Feb 2007 16:15:00 +0000Ring network topologies, bridging and routing
http://WWW.sabi.co.UK/blog/0702feb.html?070225#070225b
Single or dual ring network topologies have some nice
properties, and there are even spanning tree algorithms
specially designed to take advantage of them.resilienceEthernetnetworkingnetwork administrationhttp://www.sabi.co.uk/blog/0702feb.html?070225#070225bSun, 25 Feb 2007 15:25:00 +0000Not so good USB network adapters
http://WWW.sabi.co.UK/blog/0702feb.html?070225#070225
Some USB network adapters have a 100mb/s Ethernet
interface but a 10mb/s USB interface, and are quite unreliable
too.hardwarenetworkingEthernetUSBhttp://www.sabi.co.uk/blog/0702feb.html?070225#070225Sun, 25 Feb 2007 14:05:00 +0000Multiple interfaces on the same LAN
http://WWW.sabi.co.UK/blog/0702feb.html?070223#070223
It is possible to have multiple interfaces from one
node to the same LAN, but it is awkward.system administrationnetworkingEthernetLinuxhttp://www.sabi.co.uk/blog/0702feb.html?070223#070223Fri, 23 Feb 2007 20:50:00 +0000Multiple subnets (and VLANs) on the same LAN
http://WWW.sabi.co.UK/blog/0702feb.html?070218#070218
Running multiple subnets (especially if inside VLANs)
on the same logical or physical LAN often requires routing and
usually impacts available bandwidth. Never mind complicating
things and making them more fragile.network administrationEthernetnetworkinghttp://www.sabi.co.uk/blog/0702feb.html?070218#070218Sun, 18 Feb 2007 12:30:00 +0000Laptops as servers
http://WWW.sabi.co.UK/blog/0701jan.html?070128#070128
Modern laptops are so powerful that they can be not
just desktop replacements, but also high reliability and
resilience servers, with a built in UPS, and with CardBus or
ExpressCard one can add to them FireWire 800 and eSATA host
adapters to support fast large external hard drives.system administrationstoragenetworkingservershttp://www.sabi.co.uk/blog/0701jan.html?070128#070128Sun, 28 Jan 2007 17:10:00 +0000More RAID5/RAID6 madness
http://WWW.sabi.co.UK/blog/0701jan.html?070127#070127
Among interesting descriptions of developments
in computing at large physics research sites, amusing news about
a largish RAID6 based storage system.storagesystem administrationRAIDhttp://www.sabi.co.uk/blog/0701jan.html?070127#070127Sat, 27 Jan 2007 10:35:00 +0000Crazily high cable prices
http://WWW.sabi.co.UK/blog/0701jan.html?070122#070122
Spotted impressively high prices for ordinary
computer cables. Online too.cablesshoppinghttp://www.sabi.co.uk/blog/0701jan.html?070122#070122Mon, 22 Jan 2007 21:00:00 +0000Simple configuration-driving environment variables
http://WWW.sabi.co.UK/blog/0701jan.html?070120#070120b
A few environment variables can be a nice
orthogonal base for configuration space, especially
shell-script configuration files.UNIXLinuxsystem administrationshellhttp://www.sabi.co.uk/blog/0701jan.html?070120#070120bSat, 20 Jan 2007 23:15:00 +0000Impressive FireWire 800 performance
http://WWW.sabi.co.UK/blog/0701jan.html?070120#070120
Amazing performance of FireWire 800, where the same
disk runs 2-3 times as fast with it than with FireWire 400 or
USB2, and at speeds near those of SATA.storagehardwareUSB2SATAUSB2IEEE1394FireWirehttp://www.sabi.co.uk/blog/0701jan.html?070120#070120Sat, 20 Jan 2007 09:55:00 +0000Trying two recent branded external hard drives
http://WWW.sabi.co.UK/blog/0701jan.html?070115#070115
I have just tried two branded external USB2 hard
drives, and they seem to work fine, and fairly quickly, and
without the power supply issues that come from underspecified
power bricks. But eSATA is going to be hopefully much
better.storagehardwareUSB2SATAUSB2IEEE1394FireWirehttp://www.sabi.co.uk/blog/0701jan.html?070115#070115Mon, 15 Jan 2007 22:25:00 +0000Parallel system with low power multi-CPU chips
http://WWW.sabi.co.UK/blog/0701jan.html?070108#070108
SiCortex has launched massively parallel low power
systems based in 6-CPU MIPS chips based on the idea that low
power is good and memory stalls are bad.architecturehardwareparallelCPUhttp://www.sabi.co.uk/blog/0701jan.html?070108#070108Mon, 08 Jan 2007 22:10:00 +0000The DNS, interfaces, nodes, directories and naming schemes
http://WWW.sabi.co.UK/blog/0701jan.html?070105#070105
The DNS is a hierarchical linearized scheme for
naming interfaces, not computers or other nodes. But people
don't think in terms of interfaces, and nodes with multiple
interfaces on multiple subnets pose some naming issues. Some
alternatives are briefly discussed.networkingsysadmInternetDNSnaminghttp://www.sabi.co.uk/blog/0701jan.html?070105#070105Fri, 05 Jan 2007 21:45:00 +0000