Software Raid: system requirements
 

Hello,

I need to RAID a file server in a corporate situation. In the server is a p3 1gz, 1gb of ECC SDRAM RAM and two identical 250gb ide hard drives. Onboard, I have a Fasttrak 100 ATA RAID controller, however, it appears that this doesn't openly support linux.

This file server hosts a number of clients' data and will be hosted in a data center, therefore the Internet connection is the bottleneck, not the speed of my computer. It will probably be receiving between 5GB to 7GB transferred to it during a 12 hour period (ie overnight).

My question is: could my server, with these specs, cope with this level of data transfer?

If not, would a second 1ghz p3 make it better?

Thanks
Hamish

Thanks in advance for your help.
Hamish

I see no reason why not. So long as you have that much network bandwitdh that machine should have no trouble handling the transfer.

Get some monitoring tools so you can watch it. If you use X, get gkrellm, or if you use command line look at iptraf and others, or some here;
http://www.slac.stanford.edu/xorg/nmtf/nmtf-tools.html

Look at monitoring your cpu, disks IO, and bandwidth.

hey

thanks for your responses. I will do what you suggest.

One last question: I know that it is the CPU which is really pounded with software RAID, but is the RAM used a lot of well, given that the incoming data will need to be stored somewhere temporarily while it is written to both disks? Would adding another 2gb of swap help this?

cheers
hamish

It's going to depend on a lot of things.... hardware cache, harddrive ram, some decent HD controller, etc.... It looks like you have plenty to start with and can make a better decision after you monitor the system.

I have a box with fair amount of system cache, 500mhz/256ram, and 8 meg on each drive. Coping 1gig on the same box used avg 15% CPU with little increase ram usage. Lots of heavy web sites are running 500mhz-1gig CPU.

In your case, the network will be the slowest link. Get the best NIC you can and monitor the results.

As far as RAID goes, some of the "Hardware" RAID cards you buy actually implement software RAID through the CPU. The main thing with software RAID is make sure you have the drives on a seperate bus.

I don't see much value in adding more swap. Knowing how the linux virtual memory system works, I think if your pounding swap with a GB of RAM your in a good bit of trouble or your running a rediculous amount of memory intensive apps on there.

5-7GB over a 12 hour period really isn't that big a deal. If you think about that, its 56 Gbits in 43,200s which means you need to average about 1.33 Mbits/s over that time period if I'm doing my math right (57,344 Mbits/43,200s). That is about 170 KBytes/s transfer. So long as your internet downlink can handle that, I'm quite certain your computer can. In fact, that wouldn't even come close to taxing your local network bandwidth.