Marcus wrote to me a few days ago regarding this VPS offer from XenVZ — a 32MB guaranteed/48MB burstable OpenVZ VPS for 0.99 British Pound. That could very well be the cheapest virtual server available (a time limited promotion though). However, working with merely 32MB of memory could be tricky (especially on an OpenVZ VPS). At the end Marcus wrote:

THANKS IN ADVANCE, I hope with your help, be able to create the world est tiny server ever made :)

Well. Challenge taken :)

Signing Up

VPS provisioning at XenVZ is almost instantaneous. After submitting the form, within minutes the invoice with payment options was received. I paid with PayPal, and again within a minute my tiny VPS was built and activated. Perfect score here.

I am running Debian 5 Lenny 32bit on this VPS (which is quite a lot lighter than 64bit).

VPS Specification

Basically, you get what you pay for.

• 32MB guaranteed/48MB burstable memory
• 1.5GB disk storage
• 10GB/month data transfer

The CPU on the physical box is not too bad either:

# cat /proc/cpuinfo
processor       : 0
vendor_id       : GenuineIntel
cpu family      : 6
model           : 23
model name      : Intel(R) Xeon(R) CPU           L5410  @ 2.33GHz
stepping        : 10
cpu MHz         : 874.999
cache size      : 6144 KB
...
processor       : 1
vendor_id       : GenuineIntel
cpu family      : 6
model           : 23
model name      : Intel(R) Xeon(R) CPU           L5410  @ 2.33GHz
stepping        : 10
...

You get access to two Xeon L5410 CPU cores, but both of them has been throttled to 875MHz. However it does feel quite snappy when I navigate around and tried a few commands. Let’s now look at the dreaded user_beancounters settings on this OpenVZ VPS:

# cat /proc/user_beancounters
Version: 2.5
       uid  resource     ...   barrier                limit
     1950:  kmemsize     ...   3276800              3604480
            lockedpages  ...        64                   64
            privvmpages  ...     12288                12288
            shmpages     ...      8192                 8192
            dummy        ...         0                    0
            numproc      ...        64                   64
            physpages    ...         0  9223372036854775807
            vmguarpages  ...      8192  9223372036854775807
            oomguarpages ...      8192  9223372036854775807
            numtcpsock   ...        96                   96
            numflock     ...       100                  100
            numpty       ...         8                    8
            numsiginfo   ...       500                  500
            tcpsndbuf    ...    167772               335544
            tcprcvbuf    ...    167772               335544
            othersockbuf ...    167772               335544
            dgramrcvbuf  ...     83886               167772
            numothersock ...        96                   96
            dcachesize   ...    524288               539648
            numfile      ...      1024                 1024
            dummy        ...         0                    0
            dummy        ...         0                    0
            dummy        ...         0                    0
            numiptent    ...       250                  250

From what I can tell, the user beancounters parameters severely limits what this VPS can do. Well, you do not expect to serve millions of pages a month from just 32MB of memory, but some of the settings make it not even usable as a private proxy or VPN.

• 3.2MB of kernel memory is not a lot when you start adding some iptable rules.
• 164k of tcpsndbuf and tcprcvbuf means it could be very difficult to stream big chunk of data over TCP connections. I had hit the limit of tcprcvbuf a couple of times myself.
• Maximum 96 TCP sockets and 1024 opened files. I can think of quite a few apps breaking these params.

Anyway. It’s a tiny VPS with limited applications. Shell server? IRC node? Backup NS or MX? Now I have this VPS for 6 months (you have to prepay 6 months). What can I do with it?

I guess I will run it like what most people would use a VPS for — turn it into a web server to host websites!

Lightweight Web Server

When I first got the VPS, it runs almost nothing — not even syslog or cron. Here are the software I removed and then installed to turn it into a small web server.

• Removed:
  • DenyHost (memory-heavy as it’s coded in Python. Some iptables rules should be sufficient)
  • Removed: rsyslogd (allocates lots of memory — 20+MB!)
• Installed:
  • dropbear (to replace openssh)
  • nginx (as web server)
  • php5-cgi (to serve dynamic content)
  • dash (to replace bash as scripting shell)
  • pdksh (to replace bash as interactive shell)
  • inetutils-syslogd (to replace rsyslogd)

Please see my previous Debian 5 setup guide for more details. I am running a single process of php-cgi talking to Nginx using FastCGI protocol. The plan is to run some kind of CMS using PHP. However I do not wish to run MySQL because of its memory requirement — I am opting for something using flat files instead. At the end, DokuWiki was chosen because it’s quite flexible and uses only flat files to store all its data.

I am also cheating here — I don’t run a MTA. Instead, I use ssmtp to forward email to my other VPS for delivery.

End result?

Low End Box Wiki!!!

Yup — the entire wiki site runs on a VPS with only 32MB of memory, and the performance feels okay as well. There is only one PHP backend so there can only be one page-generation request at the same time. Not a big deal I guess judging by how many visitors that wiki might get.

# free
             total       used       free     shared    buffers     cached
Mem:         49152      17236      31916          0          0          0
-/+ buffers/cache:      17236      31916
Swap:            0          0          0

# df -h
Filesystem            Size  Used Avail Use% Mounted on
/dev/simfs            1.5G  339M  1.2G  23% /
tmpfs                 2.0G     0  2.0G   0% /lib/init/rw
tmpfs                 2.0G     0  2.0G   0% /dev/shm

I am heading to sleep now. Hopefully it is still alive when I wake up tomorrow morning :)

Updates: I am up! Trying to set up iptables and found quite a few modules are missing.

• No LOG target
• No state module

That certainly makes implementing a stateful firewall a bit trickier…

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LEA

The Founder at LowEndBox

The original owner of LowEndBox known as LowEndAdmin or LEA for short founded LowEndBox in 2008 and created the concept of hosting applications on low resource Low End Boxes. After creating the roots of the community that we know today, LEA stepped aside and allowed others to carry the torch forward.

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