[thollida]

Ok, this has got to be one of the most bizarre problems I've ever seen. I have a media server with the following specs


Athlon 2600

512mb RAM

1TB RAID 5 Array consisting of 6x200GB WD 7200 8MB Hard drives

The RAID array is done in software through Windows 200 Advanced Server



The client is


Shuttle SFF SB61G

P4 2.4 GHz

1 GB RAM

Radeon 9000



I'm using Daemon tools to mount the ripped iso of a dvd over the network. So the dvd iso is on the server, I share the iso through Windows, then mount it on the HTPC using Daemon Tools. Then I try to play it back using Theatertek 2.


I am having horrible stuttering problems. I'm sure this isn't a cpu usage problem since I've been logging cpu usage and it stays pretty low. I have set my page file size to zero and disabled QoS on the network interface. For the life of me I can't figure out what's going on. Also, I JUST upgraded this box to Windows XP with all the new patches and so on. When I had Windows 2000 on there I didn't have any issues.


I tried to just transfer the iso directly across the network and here's what the performance looks like

http://www.stanford.edu/~thollida/untitled.JPG


I can't figure out why it's peaking like that. Also, does anyone know of a utility that will allow read-ahead caching of a dvd-drive mounted on a network? That might fix my problem.


Thanks for any help!!

 

[thollida]

Just a follow-up on the above problem. It seems like Dvdidle helps a bit. This makes sense since it buffers the DVD for me. However, this still seems like a problem that I should be able to correct.


Why the heck is the network bit-rate oscillating like that? It's so regular that there must be something causing it.

 

[big boi]

there are 2 problems. first, check the CPU usage on your server, not the HTPC you are playing the dvd from. i guarantee you it is working hard. you should NOT be running raid5 through windows. raid 5 is the most demanding raid mode to run as the complexity of mathematical calculations is enormous. you are not even doing it on one of those cheapo raid cards that does the calcs via software but at least provides some onboard cache to help- you are doing it entirely in software and using your XP 2600 and system RAM for the task. even if your CPU usage is not enormous on the server windows 2000 will never do a very fast raid5 for you.


benchmark your array if you feel the need. you are better off putting all the disks in on their own and if you want redundancy just use a batch job to copy and sync up the contents of disks 1, 2, and 3 with disks 4, 5, and 6. set a scheduled job to run it every night.


secondly, never disable the pagefile. this is a stupid recommendation that is made ALL THE TIME. buy 5GB of ram and disable the pagefile. your box0r will r0x0r. wrong. at the core of windows is the Virtual Memory Manager. when you disable the pagefile you do NOT disable the VMM. you cripple its ability to function properly. from the forums @ 2cpu.com:

Quote:

[Q]Should I remove the pagefile for higher performance? Do not remove or cripple the pagefile. You are NOT eliminating paging by doing so - all you are doing is forcing all paging to be done to pages containing code and mapped files. This cripples the file cache and slows down code execution, among other things. Sure, experiment all you like. When you're done, put the pagefile back. The balance set management stuff in the NT family was deisgned with the expectation that the pagefile would be there, and it works best when you don't violate its assumptions.

 

[thollida]

Thanks for the info. I did check the CPU usage on my server and it was

 

[big boi]

software raid of any kind is going to work more slowly than hardware raid. that being said- i know the raid built into windows in particular provides pretty poor performance. linux is probably better and those people may not have these problems as a result.


you are right- the writing is MORE complex, but reading is not going to be fast using the windows software raid. the CPU still needs to determine where the stripes are that contain the data you want, retrieve them, then put them back together in order. in addition, if this is an IDE setup then you have the additional problem that IDE disks require a few CPU cycles even in a normal setup just for normal access. plus, if you have 4 drives connected to 2 IDE ports you will need to access all 4 drives in the array to get the data you are reading, BUT IDE only allows the CPU to communicate with a single drive per port at a time. so 1 drive on each port will be accessed simultaneously, and the system has to wait for those requests to finish before it can process the requests for the data on the other 2 disks.


as you can see this is a really subpar way to store and access your data from a performance point of view. as far as data security goes though you are on the right track.


in any case, the spikes in traffic arer probably due to the fact that the server is building chunks of data from the disks to send back to the client system, and then it is bursting them across the network. then as it waits a moment to build another chunk of data (remember your disks are waiting to be accessed and the software raid is somewhat slowly turning out the read requests) there is a valley in your network usage.


the fact that your CPU usage is at 40% tells me your server is working very hard to perform this raid. and the fact of the matter is that it is simply incapable of doing it in an efficient enough manner to give you the DVD playback performance you desire.


in short, i don't think your network performance is the issue at all. i think the problems you are seeing (including the spikey network utilization) are a direct result of your disk setup. if you want to test this out, i would put a single non-raided disk on it's own IDE port. save a DVD to the disk. try playing it back across the network. i would be willing to bet it does not have a problem.