January 2013 - main

Reassembling RAID array
by Mark Rogers 10 Jan '13

10 Jan '13

I had a RAID5 array set up as /dev/md1 using 4 external USB3 drives. Following a reboot (I assume, although to be honest I'm not sure what caused it) the array hasn't come back up correctly: $ cat /proc/mdstat Personalities : [linear] [multipath] [raid0] [raid1] [raid6] [raid5] [raid4] [raid10] md1 : active raid5 super 1.2 level 5, 512k chunk, algorithm 2 [4/0] [____] md0 : active raid5 sda1[0] sdb1[1] sdd1[3] sdc1[2] 5860535808 blocks level 5, 64k chunk, algorithm 2 [4/4] [UUUU] unused devices: <none> Note: /dev/md0 is a separate array and is working fine; md1 should comprise sd[fghi]1 All the "missing" partitions are present, eg: $sudo fdisk -l /dev/sdf Disk /dev/sdf: 2000.4 GB, 2000398934016 bytes 81 heads, 63 sectors/track, 765633 cylinders, total 3907029168 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x2c2d5341 Device Boot Start End Blocks Id System /dev/sdf1 2048 3907029167 1953513560 fd Linux RAID autodetect (same applies for the other three disks). How do I get mdadm to add my disks into the array, both now and after a reboot? -- Mark Rogers // More Solutions Ltd (Peterborough Office) // 0844 251 1450 Registered in England (0456 0902) 21 Drakes Mews, Milton Keynes, MK8 0ER

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Best way to code a linux comms daemon
by Mark Rogers 09 Jan '13

09 Jan '13

Occasionally I have the need to write some communications software, typically something that connects to a serial or TCP port, writes requests and reads responses, writing the results into a database. Usually the basics are simple enough to achieve, but the challenge is in making a robust solution that will cope with lost connections and any other variety of reasons why things might go wrong (including bugs in the script itself). What is the "best" way to approach something like this? Are some programming languages better than others for this? What's the best way to ensure a script restarts if it fails for some reason? I'm looking for something Debian/Ubuntu based if relevant. [Aside: One reason for asking is that I have been playing with an app I downloaded that talks to CurrentCost power meters, with a PHP-based web interface and a Python-based daemon, and I'm not sure why Python was chosen for it; also I note that the daemon regularly crashes on my system leaving me without any data.] -- Mark Rogers // More Solutions Ltd (Peterborough Office) // 0844 251 1450 Registered in England (0456 0902) 21 Drakes Mews, Milton Keynes, MK8 0ER

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Re: [ALUG] Best way to code a linux comms daemon
by Barry Samuels 09 Jan '13

09 Jan '13

On 09/01/13 09:30:13, Mark Rogers wrote: > On 8 January 2013 09:43, Barry Samuels > <bjsamuels(a)beenthere-donethat.org.uk>wrote: > > > I also use the Python-based interface written by Dale Lane. I have > > to run that 3 times every 24 hours to store data for the bar graphs > > and don't understand Python enough to be able to modify it to run > > unattended. Yes I know that there is an option to 'stay connected' > > but I don't want it running all the time just long enough to > > collect 24 hours worth of data. > > > > Cheers, I'll take a look at Dale's code, I've been using "measureit": > http://code.google.com/p/measureit/ > > I thought that I would, at least, express an interest. > > > > Thanks, it was awful quiet out there! Measureit looks interesting but appears to be for the Envi and Envir models only and mine is older than that. Pity. Some of my posts haven't appeared on the list and I haven't had a copy back but I've just realised why. I think I've been clicking 'Reply' instead of 'Reply to group' so some posts went directly to the poster instead of to the group. Apologies to those affected and old age means it can only get worse. :(( -- Barry Samuels http://www.beenthere-donethat.org.uk The Unofficial Guide to Great Britain

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Debian CDs
by James Freer 08 Jan '13

08 Jan '13

Knowing some of you use debian i just wanted to check before i download the wrong thing. If one wants a bootable (but not live CD) one just downloads the first CD of the (gulp) 53 available. I want to install xfce... so is the first one still ok? Since the last time i tried debian they seem to have liveCD iso and stick isos. Further down the list there is debian-6.0.6-i386-xfce+lxde-CD-1.iso I assume this is xfce and lxde desktops on one iso - but i can't find any info referring to it on the website. Would this be the better choice? thanks james

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HDD error
by Richard Lewis 07 Jan '13

07 Jan '13

Hello ALUG, A few weeks ago I got this error when booting my Debian box: ata1.00: exception Emask 0x50 SAct 0x0 SErr 0x280900 action 0x6 ata1.00: BMDMA stat 0x66 ata1.00: SError: { UnrecovData HostInt 10B8B BadCRC } ata1.00: failed command: READ DMA EXT ata1.00: cmd 25/00:08:00:a8:d6/00:00:3d:00:00/e0 tag 0 dma 4096 in res 51/84:00:00:a8:d6/84:00:3d:00:00/e0 Emask 0x70 (host bus error) ata1.00: status: { DRDY ERR } ata1.00: error: { ICRC ABRT } ata1.00: hard resetting link ata1.01: hard resetting link ata1.00: SATA link up 1.5 Gbps (SStatus 113 SControl 310) ata1.01: SATA link up 1.5 Gbps (SStatus 113 SControl 300) ata1.00: configured for UDMA/33 ata1.01: configured for UDMA/133 ata1: EH complete It was repeating every second or so from very early on in the boot. It did eventually boot with the root filesystem mounted read-only and the partition on which I mount /home mounted normally. In a panic, I did a backup and bought a replacement disk. Shortly afterwards I did a full SMART test and it came up clean. Since then, I haven't encountered any problems and in fact never got round to replacing the disk. (The new one is still in the packaing on the shelf.) However, this evening the same thing has happened. I did a bit more research this time and it seems this could be a SATA cable issue. The box is a Shuttle XPC which I bought as a complete system (not self-build). Does this sound like it is a problem with the SATA cable? And if so, does anyone have any recommendations or advice regarding replacing it and helping to prevent this problem in future? Thanks and best, Richard -- -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- Richard Lewis j: ironchicken(a)jabber.earth.li @: lewisrichard http://www.richardlewis.me.uk/ -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-

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[ALUG Announce] ALUG Norwich Pub Meet Thursday 10th January
by Viperfang 07 Jan '13

07 Jan '13

ALUG Announce Please send announcements to Announce(a)lists.alug.org.uk Unsub, change settings via http://lists.alug.org.uk/mailman/listinfo/announce ----- Hello Norwich Aluggers, Our monthly ALUG Norwich social meeting will be held this Thursday, 10th January at The Coach and Horses (82 Thorpe Road, Norwich, NR1 1BA). The meeting officially starts at 8pm, although some people may arrive earlier. More information on those people can be found on the list and the IRC channel. If you are unsure if you will recognise us then make yourself and your intent to attend known by either posting on list or visiting us on IRC so we can look out for you rather than hiding in the corner. Optionally you could ask at the bar if they know where the geeky computer weirdos are and they'll point you in the right direction (seriously!). Another possibility is look for heaps of electronics on a table that may possibly look like movie props that would used for detonating explosives. Feel free to bring electronics/laptops/gadgets to the meet, you will by no means be alone. Ben Bewick aka Viperfang NB: This mail is automated, please refer to the usual sources for more information. ALUG Contact Details: Website : http://www.alug.org.uk/ IRC : #alug on irc.alug.org.uk List : http://lists.alug.org.uk/mailman/listinfo Twitter : http://twitter.com/anglianlug Identica: TBA Facebook: http://www.facebook.com/group.php?gid=2381613902 ----- Send discussion replies to main(a)lists.alug.org.uk (Reply-To set) Unsub, change settings via http://lists.alug.org.uk/mailman/listinfo/announce

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USB Memory Sticks
by Michael Goddard 06 Jan '13

06 Jan '13

An odd request, but what is reasonable brand of USB M S for use with Linux? My reason for asking is that I've found of late some of these items, after a period of use, give a misleading response eg, describe item to be "full, no space", when user knows this to be untrue! tia Michael

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[OT] Google search without cookies
by Dan 06 Jan '13

06 Jan '13

Dear All, Since yesterday, Google web searches all come up blank unless I allow Google to set cookies (Firefox 10.0.7 on Gentoo). Google's privacy FAQ still says that Google search will work without cookies, and I find that Google Image, Books, and Scholar searches work just fine without cookies, so it doesn't appear to be a deliberate change of policy on Google's part. Anyone else experiencing similar symptoms? -- Thanks, Dan

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Selective 'repose' in Mint/Banshee/Brasero
by tony.anson＠girolle.co.uk 06 Jan '13

06 Jan '13

After a few minutes the (newish) netbook goes to sleep as it ought. However, when watching a video or listening to a CD (or, I presume, installing something?) the system snoozes, which is a pain. The system I'm using is the latest stable Mint put on last meeting at the Waggon and Horses. I have looked in various (IMO) likely places, but I can't find any way of disabling sleep for specific applications. Any ideas, gang? Pretty please? -- Tony

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Fwd: Re: USB Memory Sticks
by tony.anson＠girolle.co.uk 03 Jan '13

03 Jan '13

Date: Thu, 03 Jan 2013 20:35:01 +0000 [20:35:01 UTC] From: tony.anson(a)girolle.co.uk United Kingdom To: nev(a)nevilley.org.uk Subject: Re: [ALUG] USB Memory Sticks Quoting nev young <nev(a)nevilley.org.uk>: [Hide Quoted Text] On 01/01/13 10:15, Chris Green wrote: On Mon, Dec 31, 2012 at 06:50:05PM +0000, Michael Goddard wrote: An odd request, but what is reasonable brand of USB M S for use with Linux? My reason for asking is that I've found of late some of these items, after a period of use, give a misleading response eg, describe item to be "full, no space", when user knows this to be untrue! I can't reaally see why the *brand* of memory stick would affect why this might happen. Have you simply got a lot of hidden files on the stick using all the space? Chris could be right. I had a problem with losing space on the memory card in my camera which I eventually found to be all the old photos filed under .Trash I've never had that problem, and my oldest stick is 64 MB... Most of mine are now SanDisk, Peak and Kingston. Be aware that decent sticks write to the memory in a pattern, so that it is used and re-used in rotation as it doesn't last for ever. As well as Nev's good suggestion, you can delete the partition which makes the thing usable - I have a small one to which this has happened - somehow. -- Tony

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