Hardware versus Software

[AndyLiebman@aol.com]

I'm sure this has been discussed many times on the list but I was asked this 
question today and I'm not sure how to respond: 

Under Linux (i.e., a distribution such as Mandrake 10 -- with an up-to-date 
2.6 kernel), is a "true hardware RAID-5" created through a SATA card such as 
the 3ware 8506 or the new 3ware 9500 series any SAFER or MORE RELIABLE than a 
software RAID created with the same card? 

In my benchmark comparisons between software and hardware RAID, I get 
significantly better performance using "software RAID". With eight 250 GB disks, I 
get about 175 MB/sec reading and about 150 MB/sec writing when my system is 
configured as software RAID. With hardware RAID the figures drop to about 125/100 
MB/sec. 

I'm only using my machines as file servers, so they aren't busy doing any 
other tasks besides sending data packets through Gigabit Ethernet and running 
disk I/O. 

But the question still remains, is there any other safety and reliability 
advantage to using Hardware? Is the data on a Hardware RAID more likely to remain 
intact in the event of a computer crash or freeze? 

Or in the event of an abrupt power failure (I have a UPS on the system, but 
that could fail, or the power cables could be pulled out of the computer or 
somebody could accidently shut it down). All of these power failure scenarios are 
very unlikely, but they COULD occur. 

Would Hardware RAID survive better than Software? I can't see why, but maybe 
I'm missing something. 

In my situation where the server isn't running any other software, the only 
advantage I can see to hardware RAID is that rebuilding in the event of a disk 
failure is a little easier for non-experts. But I'm writing a program to 
automate the software RAID rebuilding process so that non-experts can do it 
themselves. 

Your informed comments would be appreciated. 

Andy Liebman