Software appliances – The good, the bad and the ugly

As a part of my work I have to design and plan Hardware, Systems and Software deployment, and as many of you guys know sometimes it’s not that easy. Dimensioning hardware for specific roles can be a pain, sometimes you don’t even have the software as it’s being “produced” by the development team and still you have to tell how many machines, routers, switches and all the small things the project will take.
But some other projects aren’t this difficult and you don’t need such an amount of flexibility to do them, you don’t need a custom based firewall cluster, you don’t need a web server or database cluster, you just need a simple, reliable and out of the box setup that make things work in the smallest amount of time.
When you need something like this many sys admins have an excellent way to things in a tested and production prof way (specially if they are open mined to use open source);

The Software Appliances

The appliances are really helpful  but before you start using them you need to know a few things, so lets start by the bad:

  1. Lack of flexibility
  2. Hardware choices are often hard due to  the lack of drivers/modules available

The lack of flexibility is probably the biggest problem with appliances, usually they aren’t inflexible but to master the appliance you’ll have to put a big effort on the manuals, this should’ t be a problem if you stick to a few appliances but if you use a lot of them then you’ll probably take more time to master them than to study the OS and all the applications your need (apache, samba, iptables, and so on). About hardware choices, appliances are suited to run on most hardware out there (after all they use a linux kernel, at least most of them do) but if you run cutting edge hardware you may find it hard to make it work with your appliance, specially if your appliance version as more than 6month-1year.

Let’s go to the good now:

  1. Easy installation.
  2. Fewer skills required.
  3. Dedicated support, sometimes paid, usually free from the community.
  4. Performance boost (In the cases where the appliance comes with it’s how hardware).
  5. Security.

So in conclusion appliances can be a great help, but they need extensive planning and testing before going to a production environment. Think not only about the present needs of your client but also about the future and expected ones. Bellow I’m going to write about my favorite software appliances and what are they for.

  1. dd-wrt – This is a great appliance for a bunch of Linksys, Asus, and another brand router, access point, home gateways, etc.
  2. Endian FW – Probably the appliance I use the most, you need firewall with a proxy server with content filtering? Do you need a VPN server or an antivirus scanner for your internet connection? Try this one.
  3. SME server – Do you need a windows domain server, a smtp server, pop server? Do you need to setup a small office in 2 hours? Choose SME server.

There are a lot of other appliances I’ve used since I’ve started working below a few honor mentions:

  1. GeexBox – For multimedia content displaying
  2. IPcop – Similar to endian (but endian has more features)

I’m done with appliances today, but you may wonder… what about the ugly? Well I didn’t find any that goes in this category, but the word goes well on the title 🙂 .

Cheers,

Pedro Oliveira

SD card lock switch causing problems

Yesterday while working i needed to tranfer some file to a sd card. This is a simple task, trivial thing to do but i was having trouble doing it. My card reader refused to read my SD card, no matter what i did, started looking at logs, dmesg and so on. after a while without significant info found i tried the card on a friends lap and it worked without a itch.

The only thing that showed up in var log messages was:

Jun 23 19:17:43 martini-lap kernel: sd 7:0:0:0: [sdb] Unhandled sense code
Jun 23 19:17:43 martini-lap kernel: sd 7:0:0:0: [sdb] Result: hostbyte=DID_OK driverbyte=DRIVER_SENSE
Jun 23 19:17:43 martini-lap kernel: sd 7:0:0:0: [sdb] Sense Key : Medium Error [current]
Jun 23 19:17:43 martini-lap kernel: sd 7:0:0:0: [sdb] Add. Sense: Unrecovered read error
Jun 23 19:17:43 martini-lap kernel: end_request: I/O error, dev sdb, sector 0
Jun 23 19:17:43 martini-lap kernel: Buffer I/O error on device sdb, logical block 0
Jun 23 19:17:43 martini-lap kernel: Buffer I/O error on device sdb, logical block 1
Jun 23 19:17:43 martini-lap kernel: Buffer I/O error on device sdb, logical block 2
Jun 23 19:17:43 martini-lap kernel: Buffer I/O error on device sdb, logical block 3

well the prob was the tiny switch on the SD card that allows you to lock on read only mode. The card was lacking the switch, with some adesive tape it was fixed. The strange thing is that it worked on my friends lap. Maybe it’s lap doesn’t check for the lock switch.

Hope this may help someone out there with the same prob.

Cheers.

Pedro

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