Performance problems - Upgrading

[MatiasZ]

Hi everyone. I have a Linux server at home with a 900 Mhz Duron, Asus KT400 MB, 256MB and 1x80GB ATA for the OS and 2x200GB ATA in software RAID1 used for secured storage accross the family, hosting very important and 'heavy' (audio, video) data.

However, my performance is not good. Even thow I'm on Gigabit, I can't seem to transfer anything faster than 20MB/sec peek, usually with an average of 10MB/sec, which is what I would expect for a 100mbit conexion (around 8.5MB/sec) but way off for what I need/want with gigabit.

On the other hand, speed tests on the HDs using hdparm under linux show the RAID1 setup slower to the non raid discs:

hdparm -t /dev/hda (80GB, 2MB, OS) ~52MB/sec
hdparm -t /dev/hdb (200GB, 8MB, RAID device 0) ~53MB/sec
hdparm -t /dev/hdd (200GB, 8MB, RAID device 1) ~52MB/sec
hdparm -t /dev/md0 (200GB RAID1) ~44MB/sec

If I transfer something through the network (at 100mbit as I have it right now) hosted in hda, and at the same time perform the hdparm test I get 43MB/sec for hdd, 33MB/sec for hdb and 30MB/sec for hd0. The network should only be 'eating' 10MB/sec. I can see that being as slaves is somewhat breaking the performance, but I would still expect it to be better.

OTOH, the system has an issue which makes the connection on the server go 'down' (requires me to perform 'link down' / 'link up' for it to live again) whenever I try to r/w stuff from the md0 device from a windows client. I have already swapped network cards and reinstalled/changed the OS, so it seems to be hardware related.

Bottom line is (and sory for the 'ranting' so far) I'm getting bad performance from this 'server' and it's also working funny, and these two might or might not be related. I would like to know what you guys think about these issues, if you have any feedback on the numbers or suggestions on the setup so to improve performance 'as it is', and considering I'm 99% upgrading the system (I need to buy a new MB for another PC anyway, so I might as well pass this MB to that system which is a 'client' pc and has no specific needs and get a better one for the server), what would you guys think would be a good purchase for about 200€ CPU+MB for these needs.

Regards,

Matias

 

[Frank]

For a gigabit interface, you *really* want one that is integrated into the chipset, as you hit the ceiling with a PCI solution pretty fast. Your current system is simply not able to archieve that speed. And your processor isn't helping.

Furthermore, your cabling might not allow the devices to switch to 1Gb either, as they're probably just regular Cat5.

And the speeds you get are about what I would expect with such a setup.

So, if you want to improve it:

- Check your cabling, and make sure they're all rated for 1Gb.

- Buy (or use) a motherboard with a Gb interface in or directly connected to the chipset.

- Use enough RAM (~512 MB), so the OS can buffer requests when needed.

 

[MatiasZ]

Thanks! When I tried Gigabit speeds, I tried them using a crossed cable from my PC to the server. My PC has a CSA bus for the gigabit network, so that wasn't the limiting factor, but I see what you mean for the server. I used a regular but good-enough cable for the connection, and my PC detected it as 1Gb, so I thought that was good enough (I have seen in the past computers connected to a gigabit switch and seeing 100Mb speeds because of cables as you point out).

So if I upgrade the system I would need to get a chipset capable of handling the lan interface. What others beside i865 and forward can do this? Does nForce3-4 have anything like this? From my budget I could only get a Celeron or Sempron, would this be enough processor power to handle this stuff?

 

[Frank]

Any current processor is fast enough. As for the Gb link on the motherboard, you might want to check reviews. It depends on the implementation. Most integrated ones work fine.

 

[MatiasZ]

Thanks for the input!

Back to the hard drives performance... does anybody have any input regarding problems with the setup, for example the fact they are setup as slave, etc?

 

[see colon]

about a year ago i went through a similar problem and spent the better part of a month troubleshooting the network in my spare time (it was annoying but i wasn't doing anything "mission critical" that required super fast transfers). in the end it was that i fubared configuring DMA on the server, so that might be something to look into.

 

[MatiasZ]

in the end it was that i fubared configuring DMA on the server, so that might be something to look into.

Could you expand a little bit on this? what should I be looking for?? DMA seems to be enabled on the HD on the server, but I could recheck.

 

[see colon]

the explanation is simple. i'm a linux noob and i fubared the config of a second HD i threw into my server. i thought (i gues assumed might be a better owrd) that DMA was on but it wasn't.

 

[MatiasZ]

I see. According to hdparm DMA is enabled for all the discs on the server, so that seems to be ok.

Does anyone have/had a setup like this? do you know then if the numbers are more or less the expected ones?

 

[Frank]

PM Gubbi.

 

[MatiasZ]

I'm back

I've been looking at my upgrading options and have more or less narrowed them down to the following configurations:

AMD Sempron64 2800+ BOX 60€ - Socket 754
DFI nF3 250Gb UT 85€

or

AMD Athlon64 3000+ Venice BOX 120€ - Socket 939
DFI nF3 Ultra-D 85€

I was thinking the Sempron should be enough for my needs, but buying S754 might not be the best thing although I'm not planing on upgrading this PC any time soon. However, it might be worth getting the Athlon64, and replacing it in my PC which is a P4 2.6C@3.25 and passing that to the server. How far should I be able to get the Athlon to and how would it compare to my current rig? Also to consider, I have a 6800GT AGP which I can't/won't replace for the moment, and I've read that there are some issues between nF3 and these cards. Any input, advices or comments on these paths are welcomed please

 

[Pozer]

1. Thats as fast as PCI bus/PCI card can transfer data. You need to get a motherboard with an onboard NIC to eliminate that bottleneck. ie. http://www.newegg.com/Product/Product.asp?Item=N82E16813130512

2. Your next bottleneck will be the small amount of L2 cache on that Duron. I had a Duron 1.3 as a file server and it was only on a 10/100 lan via a PCI NIC also. It would struggle tranfering files across the lan and reaching the theoritical speed limitation compared to a similar athlon XP setup. Those were windows machines though.

3. Try a Intel or 3COM NIC. They usually are less taxing on the CPU.

4. Rerun with better cabling. (cat6) Dont go over 250 feet ,(cat5e) dont go over 35 feet. just to be safe.