Hardware raid v. Software Raid v. linux raid

[Tuckie]

I'm going to be building a file server using a raid 5 with 3-5 hard drives (and planning to expand to more drives in the future) that will host dvd rips, documents, and file backups as well as other media. I'm curious as to whether or not I should go with a hardware raid solution like the Areca 1220, or a software raid card like the Rocketraid 2320, or simply using the software raid 5 that is built into linux. If I went with linux raid, I would have to either find a motherboard with six or more sata connectors, or do a mix of onboard sata and a cheap card. Do you guys think that hardware raid is worth the steep price? Or is a would I be better off with a software raid solution? Would the highpoint card be that much faster than linux raid? I plan on building it with an athlon 64 3000+ or faster and a gb of ram, btw.

 

[Matthias99]

If the CPU/memory/memory bandwidth usage is not a concern, software RAID generally works fine (whether pure software or using a 'software RAID card'). The advantage of hardware RAID5 is that CPU usage is generally very low, and models with onboard caches can sometimes improve performance.

An advantage of just doing software RAID through Windows/Linux is that you can easily transfer the array to another system. Also, if you want more than four drives in an array, software RAID5/RAID6 tends to be a LOT cheaper, since you don't need RAID controllers with 8+ ports.

 

[Tuckie]

What is the advantage to a driver based hardware raid versus a pure software based raid?

 

[Matthias99]

Originally posted by: Tuckie
What is the advantage to a driver based hardware raid versus a pure software based raid?

With a controller that can basically do everything in hardware, the driver does very little except interface with that hardware. In theory this should be somewhat more reliable, and requires less CPU time (although RAID0 and RAID1 require very little extra CPU work.) For RAID5/6, a controller with a sizable onboard cache may improve performance, since it can do all the XOR calculations locally and not eat up system memory bandwidth and CPU time.

With a RAID controller that doesn't have its own onboard processor/memory, it works very similarly to pure software RAID. For RAID0 or RAID1 there is generally little difference, but RAID5/6 can require a noticeable amount of CPU power, especially at very high throughput.

 

[RMSe17]

If you are building a file server, with perhaps some processor usage (maybe media streaming?), I'd say software solution would be fine. If I were to have RAID5 on my main PC though, I would definitely get a hardware raid card (like 3ware) , or realistically, since I don't have that money, I would just use RAID0 or RAID10, since it comes to to be cheaper...

 

[nweaver]

In many cases, Linux software raid will work FASTER then hardware raid. The exception is high end controllers, and machines with high CPU/memory utilization.