December 2011 - luv-main

MySQL multi-master config ?
by Chris Samuel 07 Dec '11

07 Dec '11

Hi folks, Anyone know of anyone using this sort of config in production ? http://onlamp.com/pub/a/onlamp/2006/04/20/advanced-mysql-replication.html It's basically exploiting the auto_increment and auto_increment_offset server settings in news MySQL to avoid ID clashes between servers, and then config them to each replicate the other. It's one of those things that sounds useful, but sounds like it might have a lot of opportunity to do interesting unexpected things to your data.. Thoughts ? cheers, Chris -- Chris Samuel : http://www.csamuel.org/ : Melbourne, VIC

2 3

mysql Data truncated for column 'x' at row y warning
by Brian May 06 Dec '11

06 Dec '11

Hello, When storing a string that is longer then the table definition, is it possible to configure mysql to treat this condition as an error and abort the operation, rather then blindly truncating/corrupting the data and reporting a warning? Or does this require using transactions[1]? I thought I saw a solution somewhere ages ago, but can't find it right now. Thanks Notes: [1] IIRC transaction support requires InnoDB and some applications require MyISAM - e.g. for geospatial stuff. Of course another option would be to switch to a better DB, eg postgresql. -- Brian May <brian(a)microcomaustralia.com.au>

2 3

free hardware
by Russell Coker 05 Dec '11

05 Dec '11

Tomorrow I will pick over a pile of decommissioned computers. Probably the minimum spec will be about a 2GHz P4 desktop. There may be some servers and workstation class systems (tower systems with ECC RAM and space for 4+ disks). For most of the systems I will probably just take RAM and hard drives and leave the rest. If anyone has any need for such systems or parts then let me know. If you want a PSU then let me know if you need SATA connectors. Special requests such as for a system that has 4 DIMM slots on the motherboard are possible. Requests for particular brands are possible. I will probably see some HP, Lenovo, and Dell systems. I can bring stuff to the meeting tomorrow night. -- My Main Blog http://etbe.coker.com.au/ My Documents Blog http://doc.coker.com.au/

2 1

hardware library
by Russell Coker 03 Dec '11

03 Dec '11

We have a library which is apparently working well. I think that the next logical step would be to establish a small hardware library. There are lots of items which have mass and volume that is less than or equal to books which can be really handy to have, often available for free, but which are unreasonably difficult or expensive if you need to buy them. I think that if we had a library which had an assortment of RAM, some video cards, a few IDE and SATA hard drives, and a good quantity of each of the sizes of screw that is used in a PC case then it would provide real value for members while not being a huge effort for someone to bring to the meeting (a small bag that could be carried in one hand - even on public transport). For extra value (and a little more transportation effort) we could have a selection of cables (power, Ethernet, USB, IDE->SATA power converters, etc), a couple of PSUs (for SATA and pre-SATA systems), and some motherboards with CPUs (I was recently offered a free motherboard with a quad-core CPU). That would take it to one box that could be carried from a car boot to the meeting without much effort. If it was going to be two boxes then a selection of power-brick PSUs would be a great thing to have (I've got a Wifi AP with a dead PSU, I would love to be able to plug it into a few PSUs and see if I can get it to work). If I was going to be attending regularly I'd run this myself. But as I haven't been attending regularly I think it would be best if it was run by someone else. I can provide a good portion of the hardware described to start this off. Some of that hardware is stuff I keep because I might need it some day, but that I would give away if I could have a reasonable chance of getting something equivalent back if I ever need it. Any volunteers? -- My Main Blog http://etbe.coker.com.au/ My Documents Blog http://doc.coker.com.au/

3 3

iphone as a gsm modem
by James Harper 02 Dec '11

02 Dec '11

Google is giving me conflicting answers... I want to dial a remote gsm device via my iPhone plugged in to a PC but I'm not seeing anything that looks like it might be a modem when I do lsusb. This is obviously different than just having a data connection to the internet as the remove device isn't connected to the internet - I need to dial it directly. Can the iPhone be used as a GSM modem or is that deemed too 'legacy' these days? I'm hoping there is a usb switch app I can run to enable the modem USB interface but I'm not optimistic. Thanks James

4 9

GPT rescue
by Russell Coker 01 Dec '11

01 Dec '11

A client has an eSATA dock for SATA disks and he's been using a 2TB disk on his Mac. He says that he just came in one morning to see that it was claiming to be empty. When I ran the print command from parted I got the following: (parted) print Warning: /dev/sdd contains GPT signatures, indicating that it has a GPT table. However, it does not have a valid fake msdos partition table, as it should. Perhaps it was corrupted -- possibly by a program that doesn't understand GPT partition tables. Or perhaps you deleted the GPT table, and are now using an msdos partition table. Is this a GPT partition table? Yes/No? y Model: ATA eSATA-2 (scsi) Disk /dev/sdd: 2000GB Sector size (logical/physical): 512B/512B Partition Table: gpt Number Start End Size File system Name Flags 1 20.5kB 210MB 210MB fat32 EFI System Partition boot 2 210MB 2000GB 2000GB hfs+ Untitled A web search for what to do suggested creating a new label and using the rescue command: (parted) mklabel New disk label type? gpt Warning: The existing disk label on /dev/sdd will be destroyed and all data on this disk will be lost. Do you want to continue? Yes/No? y Warning: /dev/sdd contains GPT signatures, indicating that it has a GPT table. However, it does not have a valid fake msdos partition table, as it should. Perhaps it was corrupted -- possibly by a program that doesn't understand GPT partition tables. Or perhaps you deleted the GPT table, and are now using an msdos partition table. Is this a GPT partition table? Yes/No? y (parted) print Model: ATA eSATA-2 (scsi) Disk /dev/sdd: 2000GB Sector size (logical/physical): 512B/512B Partition Table: gpt Number Start End Size File system Name Flags (parted) rescue Start? 1 End? 2000G Information: A fat32 primary partition was found at 20.5kB -> 210MB. Do you want to add it to the partition table? Yes/No/Cancel? yes (parted) print Model: ATA eSATA-2 (scsi) Disk /dev/sdd: 2000GB Sector size (logical/physical): 512B/512B Partition Table: gpt Number Start End Size File system Name Flags 1 20.5kB 210MB 210MB fat32 All good so far! But after that I couldn't rescue any more. So I've got the partition I don't care about (the one the client didn't even know existed) but not the one with important data. I tried creating a new partition starting at 210MB but parted gave me one starting at 211MB. :( Does anyone know how to solve this? -- My Main Blog http://etbe.coker.com.au/ My Documents Blog http://doc.coker.com.au/

4 4