21610SA for software raid?

[Nechushtan]

Hi folks, I'm looking for a cheap way to get a 16 drive RAID 5 array built using mdadm. From what I've been able to find this Adaptec card is the cheapest way to get a 16disk controller on the PCI bus, but that it's RAID support is poor at best. What I was wondering is if anyone knows if it would be possible to use it just as a controller card (like many of the software-raid based "RAID" cards) and use mdadm to actually manage the array?

I've found an 8 port card that would work, but I would need two, which I could do, but would be more costly for the cards and in the use of two PCI slots.

thanks!

[deanjo]

Hi folks, I'm looking for a cheap way to get a 16 drive RAID 5 array built using mdadm. From what I've been able to find this Adaptec card is the cheapest way to get a 16disk controller on the PCI bus, but that it's RAID support is poor at best. What I was wondering is if anyone knows if it would be possible to use it just as a controller card (like many of the software-raid based "RAID" cards) and use mdadm to actually manage the array?

I've found an 8 port card that would work, but I would need two, which I could do, but would be more costly for the cards and in the use of two PCI slots.

thanks!

What is poor about it's raid support? Specifics please. If your going to go mdadm you might was well go for the cheapest fake raid or sata controllers you can find.

[Nechushtan]

Specifically I don't remember, I just read really bad things that scared me from using it's onboard RAID implementation. Google is your friend as much as mine.

the thing is, this *is* the cheapest way to get a 16 port SATA controller. I just don't know if it will allow me to disable the RAID stuff.

If you know of a cheaper PCI solution to get 16 SATA ports please let me know!

[deanjo]

Specifically I don't remember, I just read really bad things that scared me from using it's onboard RAID implementation. Google is your friend as much as mine.

the thing is, this *is* the cheapest way to get a 16 port SATA controller. I just don't know if it will allow me to disable the RAID stuff.

If you know of a cheaper PCI solution to get 16 SATA ports please let me know!

I've used many Adaptec Raid cards in the past and they have been nothing less then absolutely stellar. When it comes to HW raid cards they are by far my first choice. Granted not that particular one though.

[Nechushtan]

I've read nothing but bad things about the Adaptec RAID controllers, which would explain why they are so cheap. Anyway, I'm still looking for an answer to my initial question.

Thanks though!

[deanjo]

I've read nothing but bad things about the Adaptec RAID controllers, which would explain why they are so cheap. Anyway, I'm still looking for an answer to my initial question.

Thanks though!

Like I said if your going to use mdadm you might as well get a couple of cheap fake raid or sata cards since your not going to be using the advantages that HWRaid offers plus your gonna run into PCI bus bottlenecks.

[Nechushtan]

and like I said, this is the cheapest solution I found. I don't want to use more than one PCI slot and even if I was willing to use up a second PCI slot, I still can't find two 8port cards whose combined total cost is less, or even near, what I can get this card for.

Now, if what your saying is "no this card can't do that, go to plan B", fine I can accept that as an answer. But your not, your telling me to use a more expensive option because you don't know the answer.

[deanjo]

and like I said, this is the cheapest solution I found. I don't want to use more than one PCI slot and even if I was willing to use up a second PCI slot, I still can't find two 8port cards whose combined total cost is less, or even near, what I can get this card for.

Now, if what your saying is "no this card can't do that, go to plan B", fine I can accept that as an answer. But your not, your telling me to use a more expensive option because you don't know the answer.

The reason there isn't alot of 4+ PCI card controllers is because there are severe bandwidth issues. In a nutshell you have the 2 choices.

1) Go with the Adaptec Card and use it with it's hardware implementation. If it's like other Adaptecs you will not be able to use mdadm with it.

2) Go the 2 PCI card route but be warned that if it is a descreet controller on it it's more then likely that you may not be able use it for mdadm raid as well. With a host based card you should be able too.

Although they don't bench PCI cards here you can see the performance hit one takes going the software based route,

http://www.maximumpc.com/article/raid_controllers_compared?page=0%2C0

[npcomplete]

The thing about windows benchmarks with fakeraid controllers is that the performance is highly dependent on the driver and nvidia's and intel's windows software raid5 implementation simply suck -- compare those to Highpoint's rocketraid 2300 which is also fakeraid.

Anyways, I'd try out the 21610sa from a place where it can be returned if you have problems. BTW, it was good to know this card existed.. I wasn't aware such a card existed for this cheap. 16-port on PCI-X 133mhz is probably ok IMO since hard drives under anything but pure sequential I/O are still pretty darn slow.

An alternative is two supermicro AOC-SAT2-MV8 cards; definitely the card to get for pci(-x). Each is $97 at newegg.

1) Go with the Adaptec Card and use it with it's hardware implementation. If it's like other Adaptecs you will not be able to use mdadm with it.

2) Go the 2 PCI card route but be warned that if it is a descreet controller on it it's more then likely that you may not be able use it for mdadm raid as well. With a host based card you should be able too.

I've never used a real HW based card on linux so I'm curious as to why this is. Is it an issue with adaptec's driver or something else?

[deanjo]

Whoa Whoa whoa!!!!!

16-port on PCI-X 133mhz <<----- Do you have pci-x or pci. A PCI-X card will NOT work in a PCI slot two, completely different slots there unless they are of the same voltage and keying Also make sure that behind the slot is not blocked by a Cap or IC if plugging in a PCI-X card into a PCI slot.