RAID card: Channels vs. Ports

[attonbitusira]

I am in the process of building a file server and one question to consider is whether or not to use integrated raid provided by the motherboard, or to buy a dedicated raid card.

One thing holding me back is cost, since I know I can buy a motherboard supporting up to 8 drives in RAID5 for $150.

Today I saw a card on ncix.com claiming to have 8 channels, and support up to 8 drives. However, both the picture on ncix.com, and the picture on the manufacturer's website, indicates only 2 SATA ports on the card. Can someone explain this to me? Is it possible to "split" a SATA cable, much like the IDE cables of late, with a master and slave...

Here is a link to the card in question:
http://ncix.com/products/?sku=37999&...ure=SuperMicro

[grinder]

negative:

serial cables are point A to point B only.

I will not recommend RAID 5 "onboard", even if your budget is low for a F-serv. Drives are sooooo cheap you can have your cake and eat it too using RAID 10.

[grinder]

Pardon me attonbitusira

That card uses a SFF 8087 connector. It uses a FAN-OUT style cable... one SFF 8087 connector "fans out" to plug into 4 SAS or SATA hard drives. The illustration of that controller tells me it is a 8 port controller card.

be warned: that is a software RAID 5 card.

[lcdguy]

1. that is a dual port SAS HBA not a raid card sp just about any raid level is going to be software based.
2. It has no backplate since most Supermicro cards are designed for the UIO spec that their server cases use.

Having said that i know that card card and the uio variant are popular when compined with a norco case for a cheap entry level WHS box.

If you want real performance stick with a raid card such as the one i have (9690SA) or the intel one grinder uses. Pair it with a supermicro chasis with a sas expander and your laughing.

This is the card I'm using: http://ncix.com/products/index.php?s...ufacture=3Ware
This is the cable, for a Raid 5 (4 drives) setup: http://ncix.com/products/?sku=34961
Works like a charm.

Do some research, and you'll find out that a hardware-based card is much better than a software-based card.

[lcdguy]

Originally Posted by shaw

This is the card I'm using: http://ncix.com/products/index.php?s...ufacture=3Ware
This is the cable, for a Raid 5 (4 drives) setup: http://ncix.com/products/?sku=34961
Works like a charm.

Do some research, and you'll find out that a hardware-based card is much better than a software-based card.

yup both the 9650 and 9690 are great cards the only real big difference is the pcie bus width 4x vs 8x.

[attonbitusira]

Thanks for the input guys.

I did some research prior to posting, and was leaning more towards the software raid because of the negligible difference in performance when cost is factored into the equation.

My decision is by no means final; perhaps shaw and lcdguy could elaborate on why you chose those particular cards vs. another model, or the real world performance gain from having a hardware card? I need to justify shelling out the $300 for a 3ware or Adaptec card.

My reasoning is based on the fact that with today's processors, they can adequately compensate the required processing needed for the RAID XOR functions. Furthermore, when the RAID array has to be rebuilt, it won't be time critical (as it would be in an enterprise situation). In other words, if the only thing holding me back with software raid is the lack of dedicated processor, then why not spend the extra money on a better CPU for the whole system, so that every aspect of the computer can take advantage of it, not just the RAID array.

I'm still a fledgling RAID user; Expert opinion is welcome! :)

[lcdguy]

well i went with the 9690sa for many reasons.

1. the case i bought uses a SAS expander backplane. So at a minimum it needed to be a SAS HBA.
2. I wanted hardware RAID and this was the best bang for my buck without buying a used card.
3. It gives very good performance as well as support for up to 127 devices when using expanders.

if you decide you want to persue a 3ware card i have a sata fanout cable i don't need anymore.

Also it depends on what raid level you want to run. if your going to run raid levels 5,6 or any other raid level that requires parity i would choose a hardware card hands down since the processors on those are cards are specifically designed to do parity calculations very efficiently. Where as a normal computer CPU is not. But if your doing something like raid levels, 0, 1 or 10. Software raid would probably be fine since that's only striping and mirroring.

On the CPU item the best analogy would be. A raid process is like like a race car. It is designed to do one thing very well. go fast on a race track. but try to drive on the normal streets and even an elantra would out do it. (i don't count nascar since nascar mostly sucks and is boring. Formula 1 FTW).

[grinder]

- the difference in performance is more than you think.

- there is no need for a dedicated parity processor if you use RAID 10 instead

Originally Posted by lcdguy

Also it depends on what raid level you want to run. if your going to run raid levels 5,6 or any other raid level that requires parity i would choose a hardware card hands down since the processors on those are cards are specifically designed to do parity calculations very efficiently. Where as a normal computer CPU is not. But if your doing something like raid levels, 0, 1 or 10. Software raid would probably be fine since that's only striping and mirroring.

Exactly why I went for a hardware-based card. I also needed:

PCI-e x4 slot
Low profile, for my 2U case
Single channel, since all I needed was a RAID5 setup (4 drives).
Most of the reviews I read about Raid cards (in the same price range, or lower) gave high marks to the card I bought.
AMCC 3Ware 9650SE Serial ATA Controller Series Review - X-bit labs for example.