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Home / Articles by John Sloan

iscsi/CHAP notes

September 15, 2015 By John Sloan Leave a Comment

Having switched off unauthenticated access to the SAN on the SAN, I had to work out how to set CHAP secrets on a per-host basis and modify iscsid.conf accordingly.  Cue considerable trial and error, but it seems to be working now.  The salient points being:  There is an … [Read more...]

Problems creating VMs with virt-manager on Centos 7.1

July 21, 2015 By John Sloan Leave a Comment

This seems to have developed a couple of unhelpful quirks.   The first problem is that the default disk image file seems now to be qcow2, and there is no way to change this from the creation wizard.   The second problem is that it no longer names the disc image … [Read more...]

Extracting a PPD from Xerox

July 1, 2015 By John Sloan Leave a Comment

Or how to extract blood from a stone, linux style.   Ok.  The generic windows PPD for the Xerox 7855 doesn't quite do what we want.   The linux install on the xerox page seems to require you to set up queues and use a xerox-supplied print command.  A … [Read more...]

Configuring CUPS for papercut

June 30, 2015 By John Sloan 2 Comments

Configuring CUPS to print to papercut queues Out of the box most Linux systems (and Macs I believe) come configured to use their own local cups daemon.  The simplest way to print to papercut is to configure a queue on this service. 1. Check that client.conf isn't … [Read more...]

zfs resilver tuning

May 14, 2015 By John Sloan Leave a Comment

The zfs resilver delay is the amount of time in seconds zfs waits after any zfs io before queing any resilver operations, to avoid degrading performance. The default on oursystem appears to have the resilver delay as 2.  With that set, it takes 10+days to rebuild a disc … [Read more...]

Virt-manager and Centos 7.1 kvm hosts

May 8, 2015 By John Sloan Leave a Comment

After the upgrade from 7.0 to 7.1 I started playing with virtual kvm hosts again.  The good news is that migration seems now not to have the bug where sometimes the domain would not freeze just after transfer. The bad news is that in virt-manager on 7.1 the default mode … [Read more...]

Centos 7.1 update broke kickstart

April 20, 2015 By John Sloan Leave a Comment

Kickstart started giving a strange error about 'xfs' not being a valid default filesystem type - though it is.    I have replaced the initrd and vmlinuz served by the tftp servers with the ones from the centos/7/os/x86_64/images/pxeboot directory and it seems to be … [Read more...]

Power problems affecting user login.

March 6, 2015 By John Sloan Leave a Comment

Late on Thursday the 5th, a fault in one of our UPS systems caused some service machines to lose power.  A number of virtual services were affected, but the most noticeable effect was the loss of authentication services. The problem was noticed at approximately 10pm, and … [Read more...]

Virtual Server service issues

February 13, 2015 By John Sloan Leave a Comment

A power event caused one of our blade chassis to reboot all its servers at approximately 1am.   Some of these servers hosted a portion of our virtual machines, and the services provided by those were affected. Affected servers and services were restarted between 8:30 and … [Read more...]

Half the DPO didn’t boot to linux on Monday morning.

January 27, 2015 By John Sloan Leave a Comment

You do not have sufficient permissions to access this page.You may be able to access this content if you login. … [Read more...]

Tagged With: DPO, Linux system

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