Just how bad is software raid 5?

T

the jones2

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Jan 29, 2010
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I currently have 4 x 750gb , a 1.5gb, and a 500gb drive running in WHS. However, WHS duplication is getting too expensive to keep up with. I am pretty handy with linux, so I am thinking about moving to a software raid 5 solution with 2 separate raids - 4 x 750 and probably 4 x1.5 .

My question is: How bad will the performance be for something like this? Worse than WHS which uses no striping? This box will be a dedicated fileserver, and it has a dual core athlon 5000.

I know that HW raid is preferable, but raid cards with 6+ ports are very expensive. I can't see myself laying out $300-500 for a quality 12 port areca or 3ware card.
 
maybe try out FreeNAS? I hear a lot of good things. I wouldn't dream of windows based software raid, but a linux or freebsd based: for sure.
 
With just about any CPU made in the past few years and supported card you can easily saturate gigE.
 
Just as a thought, on four drive raid 5 arrays you are only losing 1 extra drive for WHS duplication versus parity. If you have a single GigE port, a lot of hard drives are going to get close to saturating it all by themselves.

If you were running an Intel board, the ICH10R raid 5 isn't great, but with low drive counts it would be fine. Outside of intel, I've never even considered onboard raid as a viable option. (Raid-Z(2) running on something like FreeNAS is a good option).

Also, I'm pretty sure that for <$500 you can get a decent PCIe 16-port card. When I get around to selling one of my Adaptec 31605's I fully expect to sell it for well under <$400 shipped. If you consider the 8 port dumb supermicro cards are ~$100 it isn't that much more expensive to go HW raid. Hardware raid is really great and one advantage is that you can set it up under WHS and turn off duplication so you get all of the cool WHS features.

With all that being said.
 
Depends on what software RAID you are talking about; RAID-Z (ZFS RAID-5) is pretty awesome and doesn't suffer from write-hole or other RAID-5 effects. mdadm on Linux is pretty popular for SW RAID5/6 setups as well.
 
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