I use Nagios for monitoring. Up to recently I used a regular modem to send sms text messages to various people when systems are going wrong. The way this works is by using smsclient which dials up to a TAP server. TAP is a fairly archaic way of sending messages. It's been fairly reliable however it has two major drawbacks, sending takes along time and it's limited to 160 characters. As far as I can tell it will not do long text messages. Which are really just multiple short message combined together in a special way.
I wanted a better way! Something that sounded nice was using the mobile network to send messages, that way I could bypass most of the internal infrastructure and take the notifying system as out of band as possible. After a good bit of research I finally settled on a Masetro 100 from RF Solutions. It also turns out that smstools can use it out of the box. I'm so pleased!
posted at: 16:10 | path: /2010/08/27 | permanent link to this entry
I was looking at a development web site I am involved with and I was interested in where the site was in the big bad world, so I decided to traceroute to it[1]. What seemed very unusual was that the 5th hop reported an ip address in the 10.0.0.0/8 private address space. To quote Sam "10.what now?". I'm still amazed that packets with source addresses with private addresses are routed across the internet![2]
[1] $ sudo traceroute -m 10 -N 1 -M default 78.86.199.179 traceroute to 78.86.199.179 (78.86.199.179), 10 hops max, 40 byte packets 1 80-68-93-1.no-reverse-dns-set.bytemark.co.uk (80.68.93.1) 0.389 ms 0.174 ms 0.154 ms 2 89-16-188-3.no-reverse-dns-set.bytemark.co.uk (89.16.188.3) 0.366 ms 0.440 ms 0.326 ms 3 gi4-19.cr01.thn.bytemark.co.uk (80.68.80.73) 6.822 ms 6.707 ms 7.314 ms 4 * * linx-gw1.betherenow.co.uk (195.66.224.232) 11.099 ms 5 10.1.3.177 (10.1.3.177) 9.041 ms 8.237 ms 7.706 ms 6 * * * 7 * * * 8 * * * 9 * * * 10 * * * $ $ sudo traceroute -m 10 -N 1 -M icmp 78.86.199.179 traceroute to 78.86.199.179 (78.86.199.179), 10 hops max, 40 byte packets 1 80-68-93-1.no-reverse-dns-set.bytemark.co.uk (80.68.93.1) 0.216 ms 0.134 ms 0.092 ms 2 89-16-188-3.no-reverse-dns-set.bytemark.co.uk (89.16.188.3) 0.404 ms 0.382 ms 0.451 ms 3 gi4-19.cr01.thn.bytemark.co.uk (80.68.80.73) 8.107 ms 7.459 ms 7.462 ms 4 linx-gw1.betherenow.co.uk (195.66.224.232) 7.653 ms 7.440 ms 8.356 ms 5 10.1.3.177 (10.1.3.177) 10.940 ms 20.268 ms 9.236 ms 6 * * * 7 * * * 8 * * * 9 * * * 10 * * * $ $ sudo traceroute -m 10 -N 1 -M tcp 78.86.199.179 traceroute to 78.86.199.179 (78.86.199.179), 10 hops max, 40 byte packets 1 80-68-93-1.no-reverse-dns-set.bytemark.co.uk (80.68.93.1) 0.323 ms 0.437 ms 0.200 ms 2 89-16-188-3.no-reverse-dns-set.bytemark.co.uk (89.16.188.3) 0.446 ms 0.333 ms 0.391 ms 3 gi4-19.cr01.thn.bytemark.co.uk (80.68.80.73) 7.120 ms 6.713 ms 6.800 ms 4 linx-gw1.betherenow.co.uk (195.66.224.232) 7.925 ms 7.737 ms 7.881 ms 5 10.1.3.177 (10.1.3.177) 7.816 ms 7.500 ms 8.614 ms 6 78-86-199-179.zone2.bethere.co.uk (78.86.199.179) 21.213 ms 21.239 ms 21.242 ms 7 78-86-199-179.zone2.bethere.co.uk (78.86.199.179) 20.770 ms 21.662 ms 22.061 ms $ $ sudo traceroute -m 10 -N 1 -M udp 78.86.199.179 traceroute to 78.86.199.179 (78.86.199.179), 10 hops max, 40 byte packets 1 80-68-93-1.no-reverse-dns-set.bytemark.co.uk (80.68.93.1) 0.276 ms 0.096 ms 0.091 ms 2 89-16-188-3.no-reverse-dns-set.bytemark.co.uk (89.16.188.3) 0.444 ms 0.409 ms 0.403 ms 3 gi4-19.cr01.thn.bytemark.co.uk (80.68.80.73) 6.747 ms 6.797 ms 6.844 ms 4 * linx-gw1.betherenow.co.uk (195.66.224.232) 7.620 ms 7.488 ms 5 10.1.3.177 (10.1.3.177) 8.766 ms 7.501 ms 8.638 ms 6 * * * 7 * * * 8 * * * 9 * * * 10 * * * $ $ sudo traceroute -m 10 -N 1 -M raw 78.86.199.179 traceroute to 78.86.199.179 (78.86.199.179), 10 hops max, 40 byte packets 1 80-68-93-1.no-reverse-dns-set.bytemark.co.uk (80.68.93.1) 0.314 ms 0.097 ms 0.093 ms 2 89-16-188-3.no-reverse-dns-set.bytemark.co.uk (89.16.188.3) 0.378 ms 0.412 ms 0.330 ms 3 gi4-19.cr01.thn.bytemark.co.uk (80.68.80.73) 23.388 ms 8.331 ms 7.084 ms 4 linx-gw1.betherenow.co.uk (195.66.224.232) 8.294 ms 7.517 ms 8.027 ms 5 10.1.3.177 (10.1.3.177) 8.502 ms 7.589 ms 7.450 ms 6 * * * 7 * * * 8 * * * 9 * * * 10 * * * $
[2] $ tshark -r cap -R "ip.src == 10.0.0.0/8" 177 8.113729 10.1.3.177 -> 80.68.93.148 ICMP Time-to-live exceeded (Time to live exceeded in transit) 183 8.122267 10.1.3.177 -> 80.68.93.148 ICMP Time-to-live exceeded (Time to live exceeded in transit) 187 8.130944 10.1.3.177 -> 80.68.93.148 ICMP Time-to-live exceeded (Time to live exceeded in transit) $
posted at: 22:56 | path: /2010/07/29 | permanent link to this entry
I go to spinning quite a bit and have had I think six teachers over the last year since I started. I think every teacher has one phrase they use most, this not a bad thing, it's just something I have noticed. I present an anonymous list of them here.
posted at: 21:36 | path: /2010/07/22 | permanent link to this entry
Since Christmas I have been up to loads. I went skiing in March and I went to Cuba in June. I have done well with resolutions, I managed to stay super healthy for January and managed to mostly keep to it since. However I utterly failed to read LWN :-(
I did however keep up the reading and by my standards I have read loads! So far I have read:
I'm currently reading The Magicians - Lev Grossman. I'm also almost finished the backlog of books everyone suggested after Christmas, so any recommendations we most welcome!
posted at: 22:06 | path: /2010/07/05 | permanent link to this entry
It's time for some new years resolutions! Hopefully if they are cast in stone (well blog) there is more of a chance of success.
posted at: 23:35 | path: /2010/01/04 | permanent link to this entry
I passed my amateur radio Intermediate exam, so now I can kick out 50W! My new call sign is 2E0TDS. My thanks goes to all at SADARS that helped with the practical day and two days of lectures and exams. All I need now is some sort of radio!
posted at: 15:22 | path: /2009/11/27 | permanent link to this entry
Last week I got back from a little holiday in Dublin. I went over for my cousins graduation. I had an amassing time, it was a very relaxed and slow paced get away from everything. We went to all sorts of different cafes, restaurants and live music bars in the evening. It felt so luxurious to stay in a hotel in the centre of town, we were able to roll out of which ever bar we were in, hail a cab and be back home in no time. Coming back to a made bed and fresh towels can't be beaten.
A few places stood out. One night we went for a Mexican in Acapulca which was amazing in it's self but it was topped off by their "Deep Fried Ice Cream" desert. We also went to a restaurant type cafe one day. I can't remember the name of it now, but it served the best hot chocolate I have ever had. Then there was the Queen of Tarts which is a lovely little cafe with amazing carrot cake.
We did not stay in the hotel for the whole time, the last night one of my cousins friends put us up in their amazing house. They took us to a very strange but also very cool place that only served tea. It was called The Tea Garden. It had one of the most relaxing atmospheres I have been in. It was divided up into small booths with raised floors, cushions and small tables. We took our shoes off and sat round the small table and just relaxed! The waitress then came round and was able to recommend which teas to try. It was cool socialising without booze. When the tea came the pots had little night lights to keep them warm. We then just whiled the time away chatting.
It was not all food and drink mind, we did fit in a trip to the book of kells. We finished the trip off on the last day with an late afternoon visit to Bewley's.
posted at: 21:58 | path: /2009/11/20 | permanent link to this entry
After reading depesz's great speeding-up-dumprestore-process blog post. I started thinking about how to securely transfer a file from one server to another in the fastest possible way. The problem being that scp/sftp is slow for various reasons. ftp, http, nc, cifs, rsync are all plain text so can be quickly discounted. I don't know if ssltunnel suffers from the same window limitations that ssh suffers from. I guess using a dedicated vpn would do the trick. However I liked the idea of using gpg. I was not sure which cipher to use so I decided to run a few benchmarks to see. The results are on my wiki. Once the encrypted file has been created then it can be transfered using any of the available plain text mechanisms. I think nc or ftp have the least overhead.
posted at: 16:53 | path: /2009/10/09 | permanent link to this entry
So today I played a bit with some big cheep disks. I have 3 fairly old desktops each with 4*1TB disks, all exported via ATA over Ethernet to a much more modern sort of disk head. Basically it's a "build a large store on half a shoe string" project. I've not quite got the network side of it sorted yet. Currently the disk head's gigabit card is being saturated. On a single disk node each disk can do about 80M read sustained. If all 4 are read at the same time it goes down to about 50M, which is 200M in total. Which seems quite amazing for a Pentium 4 3.0Ghz. Also this seems a bit high as the PCI bus can only do 133M, I'm guessing that the onboard sata ports are somehow separated from the extra pci sata card I added. Interestingly one disk node can sustain 80M read from disk to the disk head. Again this backs down to 30M if all 4 disks are read, thats 120M total, no surprise this is saturating the gigabit link. So the major bottleneck is the disk head. Currently max raid sync speed is 10M, ie 120M total for 12 disks. Ideally 3 nics in the disk head would be best, but then there is no way for the data to get to the disk head.
The /proc/mdstat seems quite impressive (slow rate due to mkfs):
md0 : active raid5 etherd/e3.12[12] etherd/e3.11[10] etherd/e3.10[9] etherd/e3.9[8] etherd/e2.8[7] etherd/e2.7[6] etherd/e2.6[5] etherd/e2.5[4] etherd/e1.4[3] etherd/e1.3[2] etherd/e1.2[1] etherd/e1.1[0]
10721828480 blocks level 5, 64k chunk, algorithm 2 [12/11] [UUUUUUUUUUU_]
[==>..................] recovery = 13.4% (130652288/974711680) finish=158828.3min speed=87K/sec
The mkfs looks like it won't finish for ages, also theres still not definitive information about stride, stripe and other random things.
$ sudo mkfs -t ext3 -E stride=16,stripe-width=176 /dev/soda/store
mke2fs 1.41.3 (12-Oct-2008)
Filesystem label=
OS type: Linux
Block size=4096 (log=2)
Fragment size=4096 (log=2)
670121984 inodes, 2680456192 blocks
134022809 blocks (5.00%) reserved for the super user
First data block=0
Maximum filesystem blocks=0
81802 block groups
32768 blocks per group, 32768 fragments per group
8192 inodes per group
Superblock backups stored on blocks:
32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632, 2654208,
4096000, 7962624, 11239424, 20480000, 23887872, 71663616, 78675968,
102400000, 214990848, 512000000, 550731776, 644972544, 1934917632,
2560000000
Writing inode tables: 3351/81802
posted at: 22:40 | path: /2009/09/15 | permanent link to this entry
So my gym is closed for 10 days for a refurbishment. They are going to replace all the cardio equipment with awesomely new kit. I'll be able to check my progress online and I'll be able to plug in a video iPod and watch on the screen. The problem is, while it's closed I have no gym to go to! So I decided to try some classes instead. Tonight I tried a Yoga one and it was great, both relaxing and tiring at the same time, I really enjoyed it. I think I'll be going more often in the future and hopefully it will help improve my skiing.
posted at: 22:07 | path: /2009/08/12 | permanent link to this entry
I went to Tony and Grainne and Tonys wedding on Friday. It was a lovely day and I wish them all the best in the future.
Anyway, I learnt something while at the hotel that annoyed me. The name of the meal at the wedding reception. Hint: it's not lunch. It's called the Wedding reception, I'm not entirely sure why, but it really does get on my nerves.
posted at: 20:16 | path: /2009/08/03 | permanent link to this entry
Also I'm not laughing now:
$ psql -c "select count(*) from rssr.entries where read = false;" rssr count ------- 9941 (1 row) $In other news I might be going to see "STOCKWELL: THE INQUEST" in the Landor Theatre on Monday night. My post holiday resolution is to go to London for more culture.
posted at: 00:18 | path: /2009/07/24 | permanent link to this entry
$ psql -c "select count(*) from rssr.entries where read = false;" rssr
count
-------
0
(1 row)
$
posted at: 23:53 | path: /2009/07/02 | permanent link to this entry
posted at: 21:30 | path: /2009/06/24 | permanent link to this entry
posted at: 17:05 | path: /2009/06/18 | permanent link to this entry
$ ip route show cache 192.168.1.20
$ ping 192.168.1.20
PING 192.168.1.20 (192.168.1.20) 56(84) bytes of data.
64 bytes from 192.168.1.20: icmp_seq=1 ttl=63 time=2.25 ms
From 192.168.0.1: icmp_seq=2 Redirect Host(New nexthop: 192.168.0.57)
64 bytes from 192.168.1.20: icmp_seq=2 ttl=63 time=2.34 ms
64 bytes from 192.168.1.20: icmp_seq=3 ttl=63 time=1.32 ms
64 bytes from 192.168.1.20: icmp_seq=4 ttl=63 time=1.24 ms
^C
--- 192.168.1.20 ping statistics ---
4 packets transmitted, 4 received, 0% packet loss, time 3012ms
rtt min/avg/max/mdev = 1.241/1.791/2.344/0.511 ms
$
$ ip route show cache 192.168.1.20
192.168.1.20 from 192.168.0.62 via 192.168.0.57 dev eth1
cache mtu 1500 advmss 1460 hoplimit 64
192.168.1.20 via 192.168.0.57 dev eth1 src 192.168.0.62
cache mtu 1500 advmss 1460 hoplimit 64
$
The Guide to IP Layer Network Administration with Linux is an excellent guide!
posted at: 15:46 | path: /2009/06/13 | permanent link to this entry
posted at: 14:48 | path: /2009/06/12 | permanent link to this entry
I played with fedora more today. There are loads of packages in the default repos these days. However I still find my self missing things from Debian. For example, I can't do a "yum search" while doing a "yum upgrade". Why? I also miss the small helper scripts that save on legwork. For example update-grub, in debian when a new kernel gets installed the initrd and grub gets updated and just works. With Fedora I have to manually update the grub config and if say I forget to create the initrd it, it means a trip to the 13 PC's I just upgraded!
posted at: 00:06 | path: /2009/06/05 | permanent link to this entry
posted at: 20:51 | path: /2009/05/31 | permanent link to this entry
Finaly a I have a blog!
posted at: 19:27 | path: /2009/05/27 | permanent link to this entry