For some reason, this article written in late 2008 remained unpublished. It's therefore kind of outdated.
When I took over my former work notebook (an hp nc 8000) from my (now former) company, one of the first things I did was swapping its old 120 GB disk for a new 250 GB disk. 250 GB is the biggest disk one can get in the 2.5 form factor with a PATA interface, and there is only one disk in the market, and it's made by WD. So I didn't have much of a choice and ordered one in mid August 2008. It has been working fine until it died this Friday, a mere three months after buying it. This wrecked much of my Friday and the entire weekend for me since I spent the days being a data wrangler, and without my main work tool.
This disk death was the second one this week after having one 40 GB disk (purchased in 2001) die in my other notebook on monday. I've really had it with hardware for the time being.
Continue reading "On 250 GB in an old notebook"
Four days before my wedding, I spent some time researching booting a PC from a large hard disk, where large means "larger than two Terabytes". These days, single disks are approaching this size, so we are near the state where this issue pops up for your run-of-the-mill computer rather than the data store RAID. Today, the per-gigabyte price is however still significantly cheaper if you go for a 1 T or an 1.5 T disk.
The old blog article shows that I spent considerable time in finding out today's limitations below the 2 T limit by using conventional partitioning schemes to boot a 2 T disk. Since I don't have this much storage available at the moment, I had to use virtualization and to take advantage of nearly empty virtual disks taking up much less space than their raw capacity suggests. This works fine as long as you don't start actually using the disk.
Back then, the only combination that worked for a raw disk larger than 2 T (only using the first 2 T) was Virtualbox and grub 0 (now grub-legacy). I regret to admit that the results of my experiments from June are not any more reproducible (most probably due to changes in Virtualbox since then) and that I was not able to boot any disk larger than 2 T any more, even if the partitions were well below the 2 T limit. I chose to ignore these results and to finally start the GPT research.
Continue reading "Booting from a large hard disk II"
Steinar H. Gunderson, sesse, has written an interesting article about TCP performance. I didn't find your blog's comment function, so I am commenting with a trackback. (note: which didn't work either, "The auto-discovered trackback URI does not match our target URI")
I frequently use mobile internet, using various of the German GSM/UMTS network operators, out of a moving train. As you have written, this frequently causes packet loss which is not only not caused by congestion, but sends the congestion avoidance algorithms on a false path.
For example, when the train passes through the 3575 m long Distelrasentunnel between Frankfurt and Fulda, my network link is broken for like two minutes. Passing through other parts of Germany sometimes gives me a ping response of hundreds of thousands of microseconds by virtue of the rather huge send buffer the UMTS equipment has.
In these circumstances, ssh sessions frequently take tens of minutes to notice that the network is back before the session is useable again. Frequently, it doesn't come up again before an hour has passed. And I have not found a way to work myself around this. Can you explain what's happening here, and do you have any ideas to solve the issue?
Diesen Artikel habe ich schon im Mai 2009 geblogged. Allerdings hat sich grml seitdem so dramatisch weiterentwickelt, dass ich ihn aktualisiert und mit neuem Datum versehen habe.
Update: Das hier beschriebene Verfahren funktioniert seit grml 2011.12 nicht mehr. Der Way to Go is nun grml-rescueboot.
In Mietserver-Recovery mit veraltetem Rescuesystem habe ich beschrieben, wie man grml aus dem komprimierten Image von einer Festplatte booten kann, was zum Beispiel für Rescue-Zwecke an einem Server ohne direkt zugängliche Konsole sehr praktisch sein kann. Zu dieser Zeit (der Artikel stammt aus dem März 2007) war das noch eine größere Operation mit "CD-Image loopback mounten, die einzelnen Dateien rauskopieren und an die richtige Stelle im Dateisystem werfen", mit neueren grml-Versionen ist es aber noch viel einfacher geworden.
Continue reading "grml als eigenes Rescuesystem"
Dear Lazyweb, sorry to bother you again, but I have tried to get this question answered on IRC, on Usenet and on the Samba Mailing List, and was not able to get an answer (not even a remotely clueless one) there. Can you help?
I currently have an "interesting" task to accomplish: An IT environment with about 90 % Windows and 10 % Linux machines would like to unify backup. Currently, the Windows world backs itself up to tape using Backup Exec; the Linux world has Amanda backing up to a big disk
RAID.
This RAID is acting up and is scheduled to disappear. The current plan is to back up the Linux world with Amanda to a Samba share which is then backed up to tape by the Backup Exec installation running in the Windows world.
The Linux systems are in a diffent network, and the firewall people would like to keep the ports being open between the two networks to the bare minimum. I don't want to see NETBIOS Broadcasts inside the Linux world, I don't want to see this server in any network neighborhood, and the system acting as the Samba server for the backup should have as few open ports as possible. Of course, the share should be read only and to be as secure as possible.
Continue reading "Samba Help Needed"
Dear Lazyweb, can anybody with some advanced socat-foo tell me the command line needed to have socat create a socket in the local file system and to listen on it, so that I can have Virtualbox connect a virtual serial console to it?
The material available on socat on the web is sparse, and virtualbox-related docs usually contain "tick the create pipe option", which is not helpful here since I would like to see the first output the virtual machine prints to its serial port. It would be vastly more useful to have the socket already created with socat listening so that I can immediately see what is being printed to the socket.
Traditionally, the Linux kernel is software that I compile myself from pristine upstream sources for various reasons. I have three major kernel flavours that get built (server, desktop and notebook), and I am pretty current in running a bleeding edge kernel. This is not really necessary any more nowadays, but it's a tradition that works pretty well.
My kernels get built on sid and are packaged up with kernel-package, and equivs builds a dependency helper package which pulls in the kernel's dependencies such as initramfs-tools and takes care of cross-version updates like going from 2.6.29 to 2.6.30. Up to now, I was always able to run a kernel built this way on all my systems which can range from oldstable to unstable.
Continue reading "Unified Kernel for etch, lenny and sid"
Nur eine kurze Notiz für mich selbst und alle die es brauchen können. Sei H ein zu virtualisierender Host, E der ESX-Server, auf den H virtualisiert werden soll, V der Virtual-Center-Server und C der Client der armen Sau, die das alles machen muss.
Dann spricht:
- C über die bekannten Mechanismen mit V
- C CIFS (TCP/445) und TCP/9089 mit H
- V vermutlich irgendwie mit E (das war in meinem Testsetup eh schon erlaubt)
- H https (TCP/443) und irgend ein VMware-Gedöns (TCP/902) mit E
Und wieviele hochprivilegierte Passworte hier mehr oder weniger verschlüsselt zwischen den einzelnen Maschinen ausgetauscht werden, will ich am besten gar nicht erst wissen.
I have been using current KDE since most of my Linux time (having converted over from WindowMaker to KDE 2 back in 2002). But currently, I am seriously pondering to ditch KDE since KDE upstream seems to be wildly decided to kill KDE.
I have accidentally upgraded my desktop box to KDE4 because I missed putting KDE on hold before doing a major sid update after a couple of months. KDE4's first regression immediately showed itself - the right display doesn't get any attention from KDE. It just shows up in a grey checkerboard background, it doesn't have a panel, it doesn't have a menu, right click doesn't work. It looks like the only thing one can do with it is dragging windows onto it.
With help of #debian-kde, I quickly found out about this bug in Upstream Bugzilla, which is referred from #529487 and which was marked as Duplicate of this bug in upstream bugzilla, which is one and a half years old and was marked as "severity wishlist".
Despite the splendid job that the Debian KDE team has done to sort out the KDE4 mess, it looks like KDE upstream has managed to break Dual Head Setups for one and a half years and doesn't seem to be too interested in providing KDE4 in a way that it can be compared with past versions. This is very sad and will have me shopping for a new desktop environment soon, I am afraid.
Maybe it was not a so good idea to take away KDE 3 so soon and it might have been better to keep KDE 3 in Debian. Maybe it's time to re-introduce KDE 3 as co-installable packages? I would be willing to participate in this effort as a team member.
Which other Desktop Environments and/or Window Managers should I be shopping for? I'd like to have:
- Dual-Head support (preferably with the possibility to switch desktops only on one display, but that's something that even KDE 3 cannot do yet)
- Shortcuts like "gg:search words" or "wp:search words" to immediately open google, wikipedia, the BTS or the PTS
- Overlapping windows that are not automatically resized
- A terminal like konsole which allows me to have different session in tabs and to send my input to all tabs
- A clipboard handler that will automatically pop up a window asking me whether I want to open the URL that I just marked in a browser
- Integration with the Debian menu system
I will try adding to this list over the next days when I notice a feature that I have accustomed to so badly that I don't even notice any more when I'm using it.
In Ermangelung eines besser geeigneten Mediums: Der von mir administrierte Server q.bofh.de ist derzeit down; das Rescuesystem des Hosters scheint zu versagen. Ticket ist offen; ich hoffe, dass es dieses Wochenende noch was wird mit einer genaueren Betrachtung durch den Hoster.
Leider sind die Usermailinglisten auf der Maschine selbst gehostet.
Nachtrag: Entweder hat der Support des Hosters innerhalb einer Stunde gespurt (bisher keine Rückmeldung) oder ich war zu ungeduldig. Jedenfalls war die Kiste dann knapp anderthalb Stunden nach der dritten Rescue-Anforderung wieder am Netz und ich konnte meinen eigenen Fehler beheben.
Aus meiner Inbox bei $KUNDE:
ich sitze im Homeoffice und komme nicht ans Intranet....
Pinging intranet.example.com [62.157.140.133] with 32 bytes of data:
Reply from 62.157.140.133: bytes=32 time=66ms TTL=247
Reply from 62.157.140.133: bytes=32 time=68ms TTL=247
Reply from 62.157.140.133: bytes=32 time=71ms TTL=247
Reply from 62.157.140.133: bytes=32 time=68ms TTL=247
Continue reading "T-Online-"Navigationshilfe" zerstoert Namensaufloesung im Windows-VPN"
I recently had to install Openfiler on a HP server with ten 750 GB hard disks on a cciss RAID controller, which proved to be a major nuisance. Since the customer wanted the box in service fast, I finally settled on wasting two of the disks as a 750 GB RAID 1 for the actual system (with like 10 GB actually used) while RAIDing the remaining disks together to a RAID 6 with spare disk for productive data.
During this task, I noticed a severe lack of current knowledge about modern PC architecture and how to boot from a big hard disk and decided to do some research into this direction. This article shows the first "results" that I have achived in the last few days.
Continue reading "Booting from a large hard disk"
Dear Lazyweb, I have just found out that ksynaptics has stopped working against the X in unstable, and that ksynaptics is not even in lenny, let alone in current testing and/or unstable. This currently leaves me with an unconfigured touchpad, which is a major nuisance since I have gotten accustomed to tap-dragging and touchpad border scrolling.
xserver-xorg-input-synaptics' README.Debian dates back to 2004, so I suspect that the information given there in does not any more apply to today's configfile-less X.
So, dear lazyweb, how do I get my touchpad back into the more intelligent mode? Clickable configuration preferred.
This is a rant. A rant which goes to the grub maintainers, and one that could go nearly identically to many people in the KDE environment or many other open source projects.
I really like grub. I really like grub 0.97 despite that it's been unmaintained for years and not booting on two of my important machines. I should like grub 2 because its configuration looks more straightforward and for its better features - direct booting of .iso images, from LVM and RAID. But actually, I have learned to hate grub 2 since it is not finished and badly documented, and that its existence is already being used as an excuse for grub 0's development having stopped years ago (and it being renamed to "grub-legacy" to clearly show that it's the unloved child) - and things looks like this is not going to change any time soon.
Continue reading "The grub drama"
Linux policy routing is still incredibly painful if one wants to have more sophisticated routing than just "take source and destination IP address for the routing decision". The mechanisms that have been in use seven years ago still work though, and I didn't find any possibility to do it any easier. In this article, I'll try to explain the "old" mechanisms and hope that somebody from lazyweb will comment and say "it can be done so much easier".
This is a translation of the Usenet article <gu48cs$rul$1@news1.tnib.de> in de.comp.os.unix.networking.misc in the hope that the english-speaking blogosphere can give additional insights.
Continue reading "Pushing a packet back and forth between Linux subsystems"
