Somewhere out there! » Linux

vmbuilder, virtio and fstab

Nicholas Lee — Fri, 14 Aug 2009 00:26:06 +0000

nic@vm-base:~$ sudo blkid /dev/vda2

/dev/vda2: UUID=”0c75b2dd-6c6f-4729-b041-0d95475dc171″ TYPE=”swap”

If you install a vm with vmbuilder without virtio the swap section of /etc/fstab will use /dev/sda2 instead of /dev/vda2. You can use blkid

nic@vm-base:~$ sudo blkid
/dev/vda1: UUID="bac299c4-c545-46ca-aed3-26da4a56f6d7" TYPE="ext3"
/dev/vda2: TYPE="swap" UUID="0c75b2dd-6c6f-4729-b041-0d95475dc171"
/dev/vdb: UUID="jIkLcQ-zXUo-KIWR-zvmm-cpKP-9PpT-eE9RY3" TYPE="lvm2pv"

and then add this UUID to fstab:

nic@vm-base:~$ cat /etc/fstab
# /etc/fstab: static file system information.
#                                                
proc                                            /proc           proc    defaults        0       0
/dev/sda1                                       /               ext3    defaults        0       0
UUID="0c75b2dd-6c6f-4729-b041-0d95475dc171"     swap            swap    defaults        0       0

in order to get swap working with different driver types.

Running KVM

Nicholas Lee — Wed, 12 Aug 2009 21:50:45 +0000

I’ve started running KVM recently and I’ll post a review at some point. I’m finding it very flexible and much much easier to use that Xen.

There are still a few questions regarding file caches and disk images. In general I’m happy that it’s ready for production.

Sun and IBM

Nicholas Lee — Fri, 03 Apr 2009 21:41:03 +0000

I haven’t seen much yet to confirm this deal, but if it does happen next week it mark an interesting change in course. The thing that would interest me greatly would be zfs on linux – with Sun owned by IBM and their investment in Linux it might lead to a reconcilation between Sun and Linux licenses. While Solaris has come a long way in the last couple years, but the only reason why I use solaris is zfs. Linux is still a much more flexible, effective and deployable solution.

Bind – Shared subtrees

Nicholas Lee — Sat, 13 Dec 2008 19:53:11 +0000

Shared subtrees – in depth look at bind mounts.

Windows client CIFS behavior can slow Linux NAS performance

Nicholas Lee — Fri, 12 Dec 2008 10:30:04 +0000

Windows* client CIFS behavior can slow Linux* NAS performance:-

We have compared the performance of Windows* and Linux*-based CIFS* (Samba*) servers for digital media applications and found that the ext3*-based Linux server’s throughput was up to 53% lower than the Windows server’s–although both used identical hardware (Figure 1). An XFS*-based Linux server had roughly the same performance as the Windows server. Our investigation shows that the difference lies in the filesystem allocation and handling of sparse files. In particular, the Windows client makes an assumption that the CIFS fileserver uses NTFS*, a filesystem that assumes files will be data-full (not sparse). This contradicts a fundamental assumption of ext3–that files are sparse–and leads to fragmentation of files and degraded performance on ext3. Further, we’ve seen this behavior manifested for a broad range of media applications including iTunes*.

Load average and Vmware Server Hang Fix

Nicholas Lee — Sat, 06 Dec 2008 09:37:12 +0000

Couple useful articles from Andy Millar.

Concise and clear explaination of linux load averages.
Bug fix suggestion for VMware server which can hang on installation. Remove the floppy device. I’ve got another issue where a linux vm on vmware server hangs on startup and I’ll have to try this.

Source routing for a VPN node in Linux

Nicholas Lee — Sat, 31 May 2008 22:08:00 +0000

Occansion in Linux when running a VPN you want to generate traffic from the VPN server node. By default Linux uses the IP of the interface used to route a package. The might often complicated the routing tables required at client networks.

A solution to fix this issue is to use Linux source/policy routing. For example, for node with IP 192.168.10.1 and VPN server IP 172.29.148.1, route to subnet 192.168.9.0/24 out 172.29.148.1 via 172.29.148.2 with src (source) IP 192.168.10.1:

sudo ip route add to 192.168.9.0/24 src 192.168.10.1 via 172.29.148.2

xfs and lvm snapshots

Nicholas Lee — Fri, 30 May 2008 10:31:02 +0000

You have you the following error:

kernel: XFS: Filesystem lvm(58,2) has duplicate UUID - can't mount

Using the following:

mount -o ro,nouuid /dev/vg/lvsnap /mnt/

Thanks too.

Setting Up A PXE Linux Recovery / Deployment Server using Debian Lenny/Etch

Nicholas Lee — Sat, 01 Mar 2008 01:35:34 +0000

A clear guide for setting up a PXE Linux Recovery / Deployment Server using Debian. Including Debian Installer, DBAN and a couple other useful tools.