Author Archives: Daz

Encoding Vids – Atomic advice on mencoder

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One of the writers for Atomic mag spent some time upscalling his dvd collection to 720p. This is the commandline he used in the end to get a great clear result.

commandline ;

mencoder -sws 9 -vf scale=1280:720,hqdn3d=6:5:8,unsharp=17×5:1,pp=ha:128:7/va/dr/al – ovc x264 -x264encopts subq=9:b_pyramid:weight_b:8x8dct:me=umh:cabac:partitions=all:trellis=2:mixed_refs:direct_pred=auto:psy-rd=1.0,0.2:qp=16:threads=2:nodct_decimate:nofast_pskip:bframes=6:frameref=6 -oac copy dvd://1 -o output.avi

Of course it may change depending on what you are encoding, but its a good place to start. Check the atomic fourms (au) for more detail etc…

ESX – network utilization

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One of the best articles i have found on this subject is here : http://blog.scottlowe.org/2008/07/16/understanding-nic-utilization-in-vmware-esx/

There is some additional information here on setting up an etherchannel on the cisco side : http://blog.scottlowe.org/2006/12/04/esx-server-nic-teaming-and-vlan-trunking/

This can be handy if you need a single VM to use both physical nics in a load-balanced manner – both outbound and inbound. Of course its not really that simple though. This will really only add a benefit if the VM is communicating to multiple destinations (using ip hash – a single destination from a single VM with one IP will always be limited to the same physical nic).

switch(config)#int port-channel 1
switch(config-if)#description NIC team for ESX server
switch(config-if)#int gi0/1
switch(config-if)#channel-group 1 mode on
switch(config-if)#int gi0/2
switch(config-if)#channel-group 1 mode on

As per the article ensure you are using the same etherchannel method. The first command shows your current load-blance method, the 2nd command changes it to ip hash.

show etherchannel load-balance
port-channel load-balance src-dst-ip

Another solution is to use multiple iSCSI paths. This is newly supported within vSphere, see this post on setting up multiple paths : http://goingvirtual.wordpress.com/2009/07/17/vsphere-4-0-with-software-iscsi-and-2-paths/

Here is another good article on iSCSI within vSphere : http://www.delltechcenter.com/page/A+“Multivendor+Post”+on+using+iSCSI+with+VMware+vSphere

Some important points on using EMC Clariion with vSphere : http://virtualgeek.typepad.com/virtual_geek/2009/08/important-note-for-all-emc-clariion-customers-using-iscsi-and-vsphere.html

zfs compression and latency

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Since im using ZFS as storage via NFS for my some of my vmware environments i need to ensure that latency on my disk is reduced where ever possible.

There is alot of talk about ZFS compression being “faster” than a non-compressed pool due to less physical data being pulled off the drives. This of course depends on the system powering ZFS, but i wanted to run some tests specifically on latency. Throughput is fine in some situations, but latency is a killer when it comes to lots of small reads and writes (in the case of hosting virtual machines)

I recently completed some basic tests focusing on the differences in latency when ZFS compression (lzjb) is enabled or disabled. IOMeter was my tool of choice and i hit my ZFS box via a mapped drive.

I’m not concerned with the actual figures, but the difference between the figures

I have run the test multiple times (to eliminate caching as a factor) and can validate that compression (on my system anyhow) increases latency

Basic Results from a “All in one” test suite… (similar results across all my tests)

ZFS uncompressed:

IOps : 2376.68
Read MBps : 15.14
Write MBps : 15.36
Average Response Time : 0.42
Average Read Response Time : 0.42
Average Write Response Time : 0.43
Average Transaction Time : 0.42

ZFS compressed: (lzjb)

IOps : 1901.82
Read MBps : 12.09
Write MBps : 12.28
Average Response Time : 0.53
Average Read Response Time : 0.44
Average Write Response Time : 0.61
Average Transaction Time : 0.53

As you can see from the results, the AWRT especially is much higher due to compression. I wouldn’t recommend using zfs compression where latency is a large factor (virtual machines)

Note: Under all the tests performed the CPU (dual core) on the zfs box was never 100% – eliminating that as a bottleneck.

windows 2000 – ITMU / Windows Update Issues

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Get this when doing a windows update – Error number: 0xC8000408

First check the basics, ensure that windows update is a trusted site and the seucirty level is set corretely within the Zone – test with lower secuirty to see if that resolves the problem.

If that doesnt work try the following;
1) Added the user SYSTEM with every privilege to C: and subs
2) Stopped the “Automatic Updates” service
3) Renamed the C:\WINNT\SoftwareDistribution folder
4) Started the “Automatic Updates” service again

ESX 4 (vSphere) – installation issues

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I’ve had a couple of installation issues with ESX4

One was particularly strange, the install process would freeze every now and again until i pressed a key on the keyboard. This was related to AMD’s power saving C1 mode – disable this in the bios to fix this problem.

Secondly it was a problem with my nic. Essentially i didn’t have card that was supported (realtek). After inserting a intel card all was well. This fires up a ambiguous error and cans the whole install. (lvmdriver error)

It was nice to see that my pata drive was supported – i’ve been using it for quick tests but was unsure if it was supported in vSphere. Note: i’ve got a flash card enclosure that i’m planning on using in the future, just awaiting the card.   (hopefully this saves me some power)