Tom's Blog

New Year's resolutions

2010-01-04T23:35:48Z

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.

Stay super healthy for January:
- Keeping to my minimum weekly gym schedule, 3 morning swims, 2 morning spins, 2-3 afternoon spins, 2 afternoon yogas, 1-2 weekend weights and cv.
- No snacks during the day.
- No cake or chocolate.
- Herbal tea during the day with no milk.
- No burgers, chips or beer.
- No getting drink.
- Drinking loads of water.
Read more books, not reference books, what I call story books. I think a realistic goal is one chapter a week. I have started with Terry Pratchett's "Guards! Guards!", feel free to recommend books.
Start reading LWN again.

Intermediate Exam

2009-11-27T15:22:15Z

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!

Dublin Trip

2009-11-20T21:58:04Z

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.

GPG Bench Cipher

2009-10-09T15:53:46Z

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.

Big Disk

2009-09-15T21:40:14Z

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

Yoga

2009-08-12T21:07:25Z

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.

Wedding Meal

2009-08-03T19:16:38Z

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.

I'm back from Ireland

2009-07-23T23:18:35Z

I got back on Monday night after cutting it worryingly close to get to the airport, 2 hours in advance try 40 min! Only for Ryanair to delay the flight by an hour and tell no one. Then there's the Post Holiday Blues, aka PTD. It hit bad on Tuesday night but I think I'm used to the grind stone again now.

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.

I'm off on my holidays

2009-07-02T22:53:36Z

No Internet for 2 weeks, just as I catch up on my feeds too!

$ psql -c "select count(*) from rssr.entries where read = false;" rssr
 count 
 -------
      0
      (1 row)
$

Cineworld have an public xml data source

2009-06-24T20:30:45Z

I just found out that Cineworld have a public xml data source. It's over in the syndication subdir of their main site. There are more technical details over on my CineworldScrape page. I feel a bit sad in a way, my scraper has been working for more or less 3 years now in some form or another. The annoying thing is that they don't actually export all the data I use. Being quite visual I have grown used to using the thumbnails that each movie has to help me pick which films to see. Apart from this it's a great step forward. However the problem is there's know knowing if Cineworld will pull this service or even if they want it public. For now I'll continue to use my scraper.

Passed Foundation

2009-06-18T16:05:11Z

I passed my foundation exam on Sunday. Big thanks to all the helpfull folk at SADARS. I am now M6TDS.

ICMP Redirect

2009-06-13T14:46:22Z

Today I found out where Linux exposes the extra routing information gathered from ICMP redirects. "ip route show cache" will show the entire cached routing table. It's a bit hard to read so "ip route show cache 1.2.3.4" is better. For example 192.168.1.0/24 is a network the is connected via a host on my 192.168.0/24 network. My default gateway (192.168.0.1) has a static routing entry to the host who gateways for the 192.168.1.0/24 network (192.168.0.57). So When a random host on the 192.168.0.0/24 network pings a host on the 192.168.1.0/24 network it first sends to 192.168.0.1 but it sends an ICMP redirect saying that in the future it would be better to just send direct to 192.168.0.57 in the future.

$ 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!

Libata Errors

2009-06-12T13:48:14Z

I learned over the years to read the old ide subsystem errors for Linux and genrally am able to get a feel for the sort of hardware error thats coming. However i have yet to really get a feel for the libata errors, I'm not really used to reading the errors. I friend linked me to a page on the lib ata wiki

Fedora needs legwork

2009-06-05T23:06:16Z

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!

CineworldScrape released to public

2009-05-31T19:51:53Z

I have finally documented cineworldscrape and made it available to the general public. So with any luck google will index it!

First Post!

2009-05-27T18:27:54Z

Finaly a I have a blog!