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Software RAID error
by Mark Rogers 29 May '13

29 May '13

I'm having problems understanding what is happening on my RAID array. $ cat /proc/mdstat Personalities : [linear] [multipath] [raid0] [raid1] [raid6] [raid5] [raid4] [raid10] md0 : active raid1 sda1[0] sdb1[1](F) 976629568 blocks super 1.2 [2/1] [U_] To me, that suggests that sdb has failed, however, syslog contains lots of errors on sda but no mention of sdb. Amongst the things I've learned this morning, is the fact that I'm not getting any notifications; this only came to light because a VM that is hosted on this RAID array has lost the ability to write to one of its virtual disks (but not all of them). Should I conclude that both disks have failed? What is the best route to recovery here? Ie which disk do I swap out first with a new disk? Logically swapping out sda is the only thing that makes sense to me but advice welcomed. smartctl reports that neither disk had SMART enabled, which is odd because I thought they had, so there's no information there. I have enabled it this morning but don't want to try doing self-tests at this stage unless someone more knowledgeable than me says I should. Mark -- Mark Rogers // More Solutions Ltd (Peterborough Office) // 0844 251 1450 Registered in England (0456 0902) @ 13 Clarke Rd, Milton Keynes, MK1 1LG

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Re: [ALUG] how to block new connections whilst allowing existing established
by mick 27 May '13

27 May '13

On Sun, 26 May 2013 20:34:24 +0100 Adam Bower <adam(a)thebowery.co.uk> allegedly wrote: > On Sun, May 26, 2013 at 08:09:07PM +0100, mick wrote: > > > > Before I start playing in earnest, does anyone know of a more > > elegant solution? > > Have you looked at profiling the connection length and how the client > works? I work for a CDN and to be honest since we acquired a > particular customer the scenario changed from us having a traffic > pattern that when taking a node out of our delivery group after 2 > hours it would see no connections, since this new customer even after > removing a node from delivery it will still see significant amounts > of traffic after 24 hours. > > The way we deal with it is to let some customers get "unlucky" but > then given the client immediately does a new dns lookup and goes to a > new server it means the interruption to them would be very brief. > > Anyhow, you might want to look at some kind of load balancer like > varnish for this scenario as if not a stuck connection might mean your > reboot never happens. > > Also, see if the clients can support range headers, if so they can > resume the download from the missing bit. This means it's not the end > of the world when a download fails. > Adam Thanks for this. But I should have said that my mirrors are on VMs in datacentres I don't control. So I have no chance of sticking a load balancing proxy in front of the servers. Furthermore, the "customers" are not paying me anything (I give the mirrors to the community) so I have no form of communication with them. I /could/ just be brutal, but I don't want to be - and as you will see from my answer to Nev, it turns out I don't have to be either. Cheers Mick --------------------------------------------------------------------- blog: baldric.net gpg fingerprint: FC23 3338 F664 5E66 876B 72C0 0A1F E60B 5BAD D312 ---------------------------------------------------------------------

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how to block new connections whilst allowing existing established
by mick 27 May '13

27 May '13

Hi guys I run a couple of mirrors serving "tails" over http. Occasionally I need to shut those servers down and reboot (for example I have just upgraded both of them to wheezy). Both servers are reasonably busy (they ship out about 2-3 TiB each per month) and normally have active connections at the time I want to power cycle them. Connections can (of course) come from anywhere and some people may be on slow lines and may be over half way through a download of one of the 700 meg iso files. If I simply power cycle the server they will likely lose the connection and the download. I'd like to be more friendly than that. So what I have in mind is some mechanism that I can invoke to prevent new connections being established but permit the existing ones to complete before I switch off. I've thought about cobbling together an iptables script which will change the lines: BLAH –dport 80 -m state –state NEW,ESTABLISHED -j ACCEPT to BLAH –dport 80 -m state –state ESTABLISHED -j ACCEPT temporarily and then switch it back afterwards. But I have yet to try it. Before I start playing in earnest, does anyone know of a more elegant solution? TIA Mick --------------------------------------------------------------------- blog: baldric.net gpg fingerprint: FC23 3338 F664 5E66 876B 72C0 0A1F E60B 5BAD D312 ---------------------------------------------------------------------

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Network printing again
by Chris Walker 25 May '13

25 May '13

I'm having another try at making network printing work. I bought a Buffalo ADSL router recently with the facility to print using the inbuilt USB port. I connected up the printer and tried to make my system see the it. But it never does. If I set the host address as 192.168.1.1, the system picks the port number as 9100. I've looked on the router and all I can see is a WebAccess External Port set to 9000 so I'm guessing that 9100 isn't likely to be about right. The router can also be used as a media server with a USB disc plugged in instead of the printer. If I do that, the disc is seen as smb://ap0024a5bdb4dc/disk1_pt1/ and I can see and read the files (the buffalo is seen on a wifi network as Buffalo-BDB4DC so that ties in too). But I'm still stuck as to why I can't print. Can anybody suggest a way forward please?

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Fire FTP trying to confuse me...
by Anthony Anson 23 May '13

23 May '13

and succeeding. Up to this morning Fire FTP has been intuitive and easy to use, however, from having a local and a remote side in separate panes on the same page, it has taken the liberty of listing everything on one side, and only having an upload arrow - no download one. I may have accidentally clicked something which has brought this about, but I can't find anything to restore the default position. Any ideas? -- Tony http://www.girolle.co.uk/

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DHCP Error
by steve-alug＠hst.me.uk 21 May '13

21 May '13

Hi folks, I'm confused about another thing too. I have an external backup drive, connected via a network cable. When things boot up, it gets IP addresses for its drives from my dhcp server. This used to work fine. Recently however, I find that the drive's complaining of a "DHCP network addressing problem" (according to the blinking light code!). If, before the drive boots I disable my UFW firewall with sudo ufw disable, then boot the drive, then enable the firewall, everything's OK. If I don't disable the firewall while the drive's getting an IP address, I get the error. I'm running dnsmasq as a dhcp server. My ufw rules are like this $ sudo ufw status Status: active To Action From -- ------ ---- 67 ALLOW 169.254.0.0/16 68 ALLOW 169.254.0.0/16 67 ALLOW 0.0.0.0 68 ALLOW 0.0.0.0 192.168.55.66 ALLOW 192.168.55.0/24 I've omitted 4 rules which open up specific ports, with a format like this as they're not relevant (at least I think they're not relevant) 192.168.55.66 123 ALLOW Anywhere 192.168.55.66 456/tcp ALLOW Anywhere As I understand it, the ports I need to allow access to are 67 and 68. When something asks for an IP address and it hasn't already got one, it broadcasts from the broadcast address 0.0.0.0. Sometimes, a machine will assign itself an IP address in the 169.254.0.0/16 range - e.g. a Windows machine that can't find a DHCP server on the network. If I allow this range then such machines can contact the DHCP server. The final line should allow anything with an address in the range 192.168.55.0 - 192.168.55.255 to contact any port on my server 192.168.55.66, which is where the DHCP server is. It seems to me I must have something wrong with the UFW rules, otherwise why would disabling it allow the drive to get a DCHP lease? What have I got wrong? Any ideas appreciated. Cheers Steve

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Network Engineering
by James Bensley 21 May '13

21 May '13

Hi All, I'm Not sure how many people know about the following here already, and hope fully this isn't against any list etiquette rules; I'm sure many of you use the various Stack Exchange sites, such as http://serverfault.com/, http://stackoverflow.com/, http://unix.stackexchange.com/ and http://askubuntu.com/. Now there is a new site that recently came out of Beta for public access, http://networkengineering.stackexchange.com/. If anyone has networking questions I urge you to sign up and start asking! If the site doesn't get enough traffic in this initial stages it could get shut down, and so far it is proving to be a great well of knowledge. Many thanks, James.

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Network Engineering
by James Bensley 21 May '13

21 May '13

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[ALUG Announce] 3rd Monday Monthly Ipswich Social Meeting : The Mulberry Tree
by samwise 20 May '13

20 May '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 ----- The monthly "Third Monday" ALUG Ipswich Social Meeting is back today, 20th May, at 20:00: The Mulberry Tree 5 Woodbridge Road IPSWICH IP4 2EA Tel: 01473 225776 Map/Directions URI: http://maps.google.co.uk/?q=IP4+2EA WWW: https://www.facebook.com/MULBERRYHOSPITALITY The Mulberry Tree, previously known as The Milestone Beer House, is a grade 2 listed building in the centre of Ipswich. It is located at the intersection between Woodbridge Road and the A1156, across the road from the old Odeon cinema and not far from the Regent Theatre. It re-opened on Thursday March 29th 2012 after a major refurbishment, under its original name of The Mulberry House and has already begun to regain a good reputation for its selection of beers and ales. It has a sizeable car park to the rear of the building. All are welcome, novices and experienced users. Feel free to ask for further information on the Main ALUG mailing list. Apologies for the late reminder, I was away all weekend and missed my own reminder reminder!!! Cheers, Peter. ----- 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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Debian linux 3.8 and grub
by Richard Lewis 18 May '13

18 May '13

Hi ALUG, I recently upgraded my Debian unstable system and it included the 3.8 Linux kernel. There seem to be some problems with this kernel and my wireless network card. So I just want to set the old 3.2 kernel as the default boot option for now. However, setting: GRUB_DEFAULT=2 in /etc/default/grub and running update-grub seems not to have taken effect (the 3.8 kernel still gets booted). I notice GRUB now seems to have a new initial menu with just two options (paraphrased): "Boot Debian"; "Advanced Options". Selecting Advanced Options presents the more familiar list of kernels to boot. Where did this new menu come from? Could it be interfering with my GRUB_DEFAULT=2 option? Is there a way to remove it? Or any other suggestions why my default kernel option may not be working? Thanks, Richard -- -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- Richard Lewis j: ironchicken(a)jabber.earth.li @: lewisrichard http://www.richardlewis.me.uk/ -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-

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