Want to read Slashdot from your mobile device? Point it at m.slashdot.org and keep reading!


Forgot your password?
DEAL: For $25 - Add A Second Phone Number To Your Smartphone for life! Use promo code SLASHDOT25. Also, Slashdot's Facebook page has a chat bot now. Message it for stories and more. Check out the new SourceForge HTML5 Internet speed test! ×

Comment Good Boss, No End-User Support (Score 5, Insightful) 239

Have a good boss. Really. He doesn't have to be the nice guy everybody loves. That probably won't help. His real job is to keep the management's political games away from the developers, and to translate between nerds and managers. Most times, your ideal boss will seem just to do some paper work, and not mess with nerds' stuff. From time to time, he will ask how far the project has progressed, and occasionally, he will tell you that the stuff really has do be done before a certain deadline, at least so far that the stuff does not crash within the first five minutes. And when things are really burning, he's the one that listens to you when you need someone to yell at.

That was my first boss, and I still miss his talents. My current boss is a moron. No clue of management and politics in management, no clue of project management, hardly a clue of software development, but he knows his computer well enough to find mouse, keyboard and power button. Unfortunately, this makes him think he could manage and administrate computers. And, my absolute favorite, his completely irrational optimism. If he would drive at 200 mph against a solid wall, his last words would be "I'm perfectly optimistic that I will survive the crash without a single scratch".

The most important thing: Keep end-user support away from developers. Nothing kills concentration more than a phone that rings every few minutes, with a completely clueless user on the other end of the line, telling you that his "computer does not work, and it's all your fault".

And, you may have already guessed that: My current boss forces me to support end-users, during development.


Comment daily ... (Score 3, Informative) 266

My backup runs every night, using cron, rsync and some shell scripts, based on http://www.mikerubel.org/computers/rsync_snapshots/. It writes all data on my server (mails, home directories, SVN repositiory, database, ...) to an external disk (eSATA). Hardlinks over 10 file trees for 10 days allow me to restore deleted or modified files for up to 10 days. Average backup time is less than 1 hour after the initial backup (that runs for several hours).

Workstations and laptops contain the operating systems (can be re-installed from CD/DVD/PXE), files copied from the server (local copies of mails, SVN sandboxes, ...), and some temporary files not worth to be backed up. So, I don't need to backup those machines.


Comment Do that many people still have modems attached? (Score 4, Informative) 160

Do that many people still have modems attached?

Yes. While DSL, UMTS and DOCSIS are quite common in urban areas, there are still several areas (villages) where dual-channel ISDN is the fastest way to get into the net (2x 64 kBit/s), and many people in those areas still use analog modems (V.90) simply because ISDN lines have a higher monthly fee and dual channel ISDN doubles the costs of each internet connection.

Of course, there is also satellite internet access, but it is expensive, overloaded, slow (despite opposite claims of the operators) and has a high latency. Plus, you need a free line of sight to the satellite and the permission to install a(n additional) satellite dish from the owner of the house. LTE is the latest promise for fast internet access in non-urban areas, following WiMAX. WiMAX exists only in prototype areas, it still is not commonly available in Germany. LTE is only planned, no prototype area exists, and despite legal restraints to install LTE first in areas without high speed internet connections, the first prototype areas will be big cities.

Another reason to use a modem is the ability to send and receive faxes, as others already posted.

Costs for 0900 calls are very high compared to other numbers, and the 0900 owner can define how much is charged. There are two mutually exclusive limits: Either max. 3.00 EUR per minute, or max. 10.00 EUR per call independantly from the length of the call. (Source: http://www.teltarif.de/i/sonderrufnummern-0900.html) So if you use the second option (charge 10.00 EUR per call) and distribute a dialer that makes one-second calls to your 0900 number, you gain 10.00 EUR per second and call. Gaining 8,000,000 EUR (roughly approximating 1 EUR = 1 $) requires 800,000 calls. If you can make 10 calls before getting caught by the modem owner, you need only 80,000 users. If you can make 100 calls before getting caught, you need just 8,000 users.

ISDN users are even more attractive than modem users. The V.90 handshake needs about 10 to 20 seconds, and it is noisy due to the modem speaker. Plus, the V.90 modem blocks the phone line. So it is very likely that the dialer is found very fast. The ISDN handshake takes much less time, about a second, it is silent, and ISDN offers two lines, so you can still use your phone while your computer is busy wasting your money with one second calls to a 0900 line. If that goes unnoticed for one hour, and each call lasts four seconds total, you have 900 calls from one user, 9,000 EUR. Trick just 900 users into using your dialler for one hour on an ISDN line and you gain 8,100,000 EUR.


Comment Switch back! (Score 0) 2254

Come on, this must be an April fools joke released too early!

The site is unusuable without Javascript, can't even configure without JS, no way to switch back to classic layout, lots of broken links (at least w/o JS), and the usual boring "look Ma, I can do round corners, shadows and non-scrolling sections on my web 2.0 site" shit. There is one thing that everyone writing a web site should know in 2011: Javascript is OPTIONAL. Make sure the page works 100% without Javascript. And by the way: In 2011, you should be able to produce valid HTML, encoded in UTF8. Even when working with templates. Especially when you pretend that the site is HTML5.

Summary: Slashdot new design = BIG FAIL!


Comment Only once ... (Score 1) 263

... in my last job, we had a lot of clients using Microsofts mail services. M$ gave you basically two choices: Implement SPF or have your mails delivered to the spam folder or refused. So, we made our DNS provider add SPF records and the problem was gone.


Comment VNC is the way ... (Score 5, Informative) 454

... you just need to know that your friends (and family members) DO NOT need to mess with their routers. Just YOUR router needs to open a single port (5500/tcp) and forward it to your workstation. Make your friends run the VNC server as usual, start the VNC client on your workstation in LISTENER mode, tell your friends to select "add new client" from the VNC server icon context menu, and make them enter your IP or dyndns address into the popup dialog.

(Technically, this swaps the roles of client and server on the TCP level, but VNC still behaves as expected.)


Comment Cheep Non-RAID Controller! (Score 4, Interesting) 564

Fast facts:

  • NTFS and ext3 have journaling, FAT12/16/32 and ext2 don't have journaling.
  • FAT12/16/32 have a central structure (the FAT). Damage it and your data is lost. ext2 and ext3 store their meta data redundantly.
  • RAID is no replacement for Backup.
  • A real hardware RAID is expensive, and appears to be a single disk to both BIOS and OS. Its on-disk meta data is propritary, i.e. if your HW RAID controller dies, you need exactly the same controller again to get access to your data. HW RAID works with every OS, because it appears to be a single disk (typically, SCSI). Booting from complex RAID configurations is no problem, as each RAID appears to be a single disk. The RAID controller is a small computer on its own, taking care of the reqired calculations for non-trivial RAID levels, of switching to hot-standby disks, and of detecting broken disks.
  • A software RAID is cheep as dirt, every single disk of the RAID appears in BIOS and lower levels of the OS. The on-disk meta data depends only on the OS, so you can mix controllers as you like. A broken controller is no problem, replace it with any controller that has the same connectors and your data is back. Booting can be a problem, because the BIOS does not know anything about the RAID. Usually, booting is only possible for RAID-0 and RAID-1. Booting another OS is problematic, because there is no standard for Software RAIDs. Linux may be able to work with Windows RAID volumes, but Windows can't work with Linux RAID volumes. Calculation and monitoring is done by the host CPU.
  • A host RAID is nearly as cheep, the only difference to a software RAID is that the BIOS decides about the on-disk meta data. Special drivers for each supported OS know the structure of the meta-data, but they don't allow to use other controllers in the same RAID. A broken controller is a problem, because drivers will refuse to work with other controllers. Booting is no problem, because the BIOS knows about the RAID.

I prefer pure software RAIDs, for a simple reason: They do not depend on available hardware. If one controller dies, switch to another one: Other brand, other type, other drivers, and the RAID still works. If you insist, you can even mix an IDE drive, a USB drive, a SATA drive and a SCSI drive into a single RAID. Try that with a hardware or host RAID. Some people even built RAIDs of floppy disks or USB sticks (not for pemanent use, of course).

My faithful old Linux home server runs two RAIDs, both in software: a RAID-1 for the OS (remember: the BIOS does not know about the RAID), and a RAID-5 for the data. The RAID-1 used to run on old SCA drives, but recently, I switched to two small IDE drives due to unrecoverable SCA cabling problems. The RAID-5 is composed of four IDE drives, connected to two IDE controllers, each disk on a single IDE cable. An external USB disk is used to back up my data, rotating through 10 days. All filesystems are ext3, all disks are monitored using SMART, all RAIDs are monitored. If anything wents wrong, I will get an e-mail from the monitoring software.

Until recently, one of the controllers was an el-cheapo non-RAID controller, and the other one was a donated, expensive, well-known brand, RAID-capable controller running in non-RAID mode. The latter one decided to randomly take some free time on the job, and either disconnected from the PCI bus or disturbed it, causing panics in the OS above. Only pure luck protected me from data loss. I ripped it out of the machine, kicked it into the trash bin, rewired the RAID to use two disks per IDE cable, and verified and reconstructed my data. Some days later, another el-cheapo non-RAID IDE controller arrived, the same brand, model and type that already sat in the next PCI slot. So I rewired the RAID again to work with one disk per cable, everything was fine again.

For a new small business or home server, I would use nearly the same setup again: Two software RAIDs, one for the OS, and one for the data. Upgrading the OS is just fun when you can simply copy the entire known-good OS to a backup directory on the data RAID. I would use SATA instead of IDE, simply because it is the current standard. I would use the second-largest disks available for the data RAID, and the cheapest disks available for the OS RAID, like I did some years ago. SATA has a dedicated cable for each disk, so there is no more need to avoid running disks configured as slaves, and so one controller with four SATA ports is sufficient for a RAID-5. I would pick a mainboard with lots of SATA ports, gigabit ethernet, and a mid-range CPU. For backup purposes, I would use one or two hot-pluggable, external SATA drives.

For a new, smaller home server, I would use only two disks in software RAID-1 configuration, but still split into a small OS and a large data partition, a low power CPU (Intel Atom or VIA C7), gigabit ethernet, and a USB-2.0 or e-SATA external backup disk.


Slashdot Top Deals

The amount of time between slipping on the peel and landing on the pavement is precisely 1 bananosecond.