Category Archives: Linux Virtualization

Xenserver reading–Converting-Local-Storage-to-ext3-and-thereby-enabling-sparse-provisioning

Adding removable drives

Xenserver: moving data to remote file server

I am considering moving the Xenserver machines to a network location, removing them from the box in which the hypervisor is residing.

I have a gigabit network which theoretically can transport just over 100MB/s worth of data (about 125MB/s I think is the calculation) but I expect less then that in the real world.

A 100Mb network can do 12.5MB/s, but realistically, only about 9MB/s is capable after all the networking overhead is introduced, so assuming 90MB/s for a gigabit connection may not be unreasonable.

HD normally put out 40-60MB/s, so a gigabit network should not be a bottleneck (assuming only one connection).

Going to run some tests to see what throughput my LAN can sustain.

Running bonnie++ on /mnt/tower/disk1 I get

Version 1.03d       ------Sequential Output------ --Sequential Input- --Random-
                    -Per Chr- --Block-- -Rewrite- -Per Chr- --Block-- --Seeks--
Machine        Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP  /sec %CP
apps-server05 2072M 22582  11 23699   1 15228   0 53534  35 62733   1 165.6   0
                    ------Sequential Create------ --------Random Create--------
                    -Create-- --Read--- -Delete-- -Create-- --Read--- -Delete--
              files  /sec %CP  /sec %CP  /sec %CP  /sec %CP  /sec %CP  /sec %CP
                 16   832   2  1852   1  1079   1   812   1  2153   0   840   1

Locally on the workstation running Bonnie++ on the SSD drive with a 8gig file (4gigs ram in machine) I get:

Version 1.03d       ------Sequential Output------ --Sequential Input- --Random-
                    -Per Chr- --Block-- -Rewrite- -Per Chr- --Block-- --Seeks--
Machine        Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP  /sec %CP
workstation01 7416M 63910  62 49520  20 24627  11 96748  92 233131  38  2300   9
                    ------Sequential Create------ --------Random Create--------
                    -Create-- --Read--- -Delete-- -Create-- --Read--- -Delete--
              files  /sec %CP  /sec %CP  /sec %CP  /sec %CP  /sec %CP  /sec %CP
                 16 +++++ +++ +++++ +++ +++++ +++ +++++ +++ +++++ +++ +++++ +++

On the same workstation, using a 7200rpm 160 gig drive, I get:

To be done

I did some file copies with SCP (since it reports the transfer rate).
Between machines on the xen hypervisor with a local file I am getting about 75MB/s
Between same machines, with a file stored on the UnRAID server I am getting about 30MB/s in read speed. This is obviously limited by both the UnRAID machine or the network connection.

Did another SCP between my workstation machine and a virtual machine and I topped out at 9.9MB/s
Will have to investigate this further since I’m obviously only getting 100Mbit speeds, when I have a 1Gb connection? Maybe not…

Using Suse Studio appliances

I had tried using Suse Studio appliances a while back, and didn’t have much luck with it. That was over a year ago, and honestly, I don’t remember exactly why I didn’t like it, or couldn’t get it working. I think it may have had something to do with the fact that I could not boot one of those appliances in xen or xenserver (whatever I was running at the time)

Anyway, it seems like there may be home. I came back to visit the site today, and did a bit of digging, and it seems there may be a simple way to convert the xen appliance into a Cirtix XenServer appliance. Get the python script and read the how-to here.

I will have to give this a go.

UPDATE: So I gave it a go.
After some struggling, I can report success. I have managed to get a xen vm created by suse studio to run in Citrix’s XenServer, using the script mentioned earlier.

Once the xva file is imported into xenserver (throught xen center)  I need to add “console=ttyS0 xencons=ttyS barrier=off” to the Properties > Startup options of the VM.

Currently I’m refining the one SqueezeCenter appliance VM.

XenServer 5.5.0 and IDE drives

A few days ago I moved from runing a openSuSE DomU host to the Free XenServer 5.5.0 that Citrix is offering.

I had noticed that the VMs were running very slowly. Much slower then I remembered them running on the openSuSE DomU. So I did some tests, and it came down to the  fact that hdparm -tT /dev/sda was reporting about 1-2MB/sec for the buffered disk reads. This was taken at the console of the xenserver terminal, not on a VM.

After some research, I found out that the generic IDE drivers don’t allow for UDMA to be enabled. So I did the next best thing. I had a SATA drive of similar size in another machine, and swapped the two.

Now I get about 60MB/sec buffered disk reads. That’s what it should be. And from within a VM I get about 55MB/sec, but I don’t quite believe that. Will have to do some more extensive testing with bonnie++.

HowTo: OpenSuSE 11.2 PV running on XenServer 5.5.0

I’ve been running virtual machines for a while now (maybe 3 years?) and they have all been running on some bare minimal OpenSuse installation (in Dom U) with Xen being the hypervisor.

I decided the other day to give XenServer 5.5.0 (the free version) a try. I had a few days of unhappiness, mainly because I love openSuse, and it seemed that nobody knew how to get it installed in XenServer, as a PV guest.

I finally got it working. Finally got openSuSE 11.2 running in XenServer, as a PH guest, with the Server Tools installed and working. Continue reading

New XEN virtual machine management

So after installing OpenSuSE 11.2 on the server machine, I decided to take a step back nd decide how to manage all the current and future virtual machine.

For starters, I will use LVM for the disk space they use. I have created a template/minimal install of OpenSuse11.2 into a file based VM. The file disk it’s installed on is 1GB. gzipped, the file is only 250MB.

This will be the basis/starting point for all the new VMs. I have used dd to copy the virtual file based disk to an LVM volume on any size. Once that’s done, I can resize the partition to whatever size I want. (Note 1 on resizing) I can also make as many copies I want and run them as anything I want.