Hardware raid
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raid isnt fault tolerant
I assume we're talking SATA RAID5 here?
Without knowing budgets, space requirements etc I'm going to have to be a bit vague but here goes.
Bus Type:
Any more than a pair of drives will saturate the standard PCI bus so for decent performance you'll need to look at PCI-X or more likely PCIe. You can get PCIe 1x cards but they're only 4 port, if you have a 4x slot (or 16x) you'll be able to go to 8 ports and for an 8x card there are options for 8 to 24 ports but you'll need a free 16x slot.
Hardware or Software?
In this context it's whether the card has specific on board hardware to perform the XOR calculations required for RAID5 parity. Having an onboard XOR engine will greatly improve the write speed of the array but also increases the cost of the card. There is a middle ground available from Highpoint - accelerated software cards where some of the processing is off loaded onto the main CPU and some is done on the card. This is reasonable compromise for storage arrays. For comparison a hardware based card like an Areca 1220 will be capable of writes in excess of 150Mb/s on a big array whereas a Highpoint Rocket Raid 2320 tops out at about 60Mb/s. Both cards will return a fairly similar read rate as there is no processing overhead for reads.
Which to get?
Depends on budget etc but here are some options
RocketRaid 2300: PCIe 1x, 4 port - Decent enough accelerated software card but limited by only being 4 port. Probably about £80-100.
RocketRaid 2320: PCIe 4x, 8 port - Accelerated software again but 8 ports so more capacity. Good reads with an 8 disk array but writes aren't spectacular. I use one of these cards for my storage array. Around £180-200.
Areca 1220: PCIe 8x, 8 port - Serious kit with an appropriate price tag, onboard XOR engine gives very good write speed to go with the good reads an 8 disk array is capable of. Also supports RAID6 for 2 disk failure protection. Expect to pay £300-350.
Areca 1280: PCIe 8x, 24 port - Bragging rights central! Native RAID6, up to 2 Gb of onboard cache etc etc etc. Yours for the bargain price of around £1500.
Without knowing budgets, space requirements etc I'm going to have to be a bit vague but here goes.
Bus Type:
Any more than a pair of drives will saturate the standard PCI bus so for decent performance you'll need to look at PCI-X or more likely PCIe. You can get PCIe 1x cards but they're only 4 port, if you have a 4x slot (or 16x) you'll be able to go to 8 ports and for an 8x card there are options for 8 to 24 ports but you'll need a free 16x slot.
Hardware or Software?
In this context it's whether the card has specific on board hardware to perform the XOR calculations required for RAID5 parity. Having an onboard XOR engine will greatly improve the write speed of the array but also increases the cost of the card. There is a middle ground available from Highpoint - accelerated software cards where some of the processing is off loaded onto the main CPU and some is done on the card. This is reasonable compromise for storage arrays. For comparison a hardware based card like an Areca 1220 will be capable of writes in excess of 150Mb/s on a big array whereas a Highpoint Rocket Raid 2320 tops out at about 60Mb/s. Both cards will return a fairly similar read rate as there is no processing overhead for reads.
Which to get?
Depends on budget etc but here are some options
RocketRaid 2300: PCIe 1x, 4 port - Decent enough accelerated software card but limited by only being 4 port. Probably about £80-100.
RocketRaid 2320: PCIe 4x, 8 port - Accelerated software again but 8 ports so more capacity. Good reads with an 8 disk array but writes aren't spectacular. I use one of these cards for my storage array. Around £180-200.
Areca 1220: PCIe 8x, 8 port - Serious kit with an appropriate price tag, onboard XOR engine gives very good write speed to go with the good reads an 8 disk array is capable of. Also supports RAID6 for 2 disk failure protection. Expect to pay £300-350.
Areca 1280: PCIe 8x, 24 port - Bragging rights central! Native RAID6, up to 2 Gb of onboard cache etc etc etc. Yours for the bargain price of around £1500.
kool, that has really helped cause i was looking at was the 180 - 200 pound one on yer list 
as the best solution and sorry yes it would have been sataII raid using PCI express, so thanks for the help. And would the one above be one of the ones u mentioned cause i believe it is 
cheers also the top level one tho would be nice and shiny but tooooo much money even tho it would be stupidly fast
sorry, that was silly of me to have that link *slaps self*
as the best solution and sorry yes it would have been sataII raid using PCI express, so thanks for the help. And would the one above be one of the ones u mentioned cause i believe it is cheers also the top level one tho would be nice and shiny but tooooo much money even tho it would be stupidly fastsorry, that was silly of me to have that link *slaps self*
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That's better
It's a decent wee card that, nothing special but then again it's not particularly expensive. With 8 Hitachi T7K250s which aren't particularly special these days you can get some decent read speeds out of it - 220Mb/s average! .
If you do decide to go with it post again, there are a few things I had problems with getting it going. I'd be glad to pass on the fixes.
It's a decent wee card that, nothing special but then again it's not particularly expensive. With 8 Hitachi T7K250s which aren't particularly special these days you can get some decent read speeds out of it - 220Mb/s average! .
If you do decide to go with it post again, there are a few things I had problems with getting it going. I'd be glad to pass on the fixes.
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if you work with servers you should know that raid 5 doesnt mean its fault tolerant too. Were all aware of how the array works and that you just put another drive in if 1 fails, what about when the array gets corrupt or more than 1 drive fails? if you want speed you get raid 0 and if you want to keep data safe you back up. Really dont see the point in raid 5 at all
Huh? Do you have any experience of proper data storage architectures?quantumisation said:
No one has ever claimed that any level of RAID is fully fault tolerant, there will always be some set of circumstances that will cause an array to fail. What RAID5 gives you is *availability* and redundancy in the event of a drive failure. RAID0 plus a backup is fine in a domestic situation when you can spend 2 days reinstalling the machine from the backup. However spending 2 days rebuilding a machine that's running a business process is not an option, it has to be available all the time that the business needs it hence RAID5 is appropriate.
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yea sorry i thought this was a forum for home users considering the name 'overclockers'. Could you maybe enlighten me more on 'proper data storage architectures' bearing in mind i know exactly what each raid level consists of?
quantumisation said:
Overclockers is for anyone, and was setup so we can all share information and learn from other's experiences, as well to have a laugh! Lighten up a bit mate, no need for your smart comments.
Raid 5 does provide some redundancy, 1 drive can fail and the array should still function using the distributed parity. You only really get data loss when 2 drives go at once, which is unlikely. When a drive fails you also replace it quickly to ensure the safety of data. I dont get what you mean by the array becoming corrupt. A drive failing doesnt mean the array is going to corrupt straight away. No RAID solution provides complete redundancy except Raid1 and even then, what is a server caught fire? Not much use then. RAID + backups are the way to go IMO.
That was the point, all i was after was advice on which controller to get, as software raid is not as quick as hardware raid, i mean a good example of speed is a SAN
which is silly quick, and they very clever as well which would explain y u can expect to pay silly amount and no home user would ever have one. I mean possibly the most fault tolerent would be raid 0+1 but i could be wrong and RAID 5 is considered true raid as u can in some setups lose more than one drive, or if u have hot swaps available then it will rebuild itself if its a very clever controller e.g. in a SAN or similar. What would you say is the best RAID for redundancy and mass storage e.g. lose a drive but no lose of data and say 900GB + of storage space
which is silly quick, and they very clever as well which would explain y u can expect to pay silly amount and no home user would ever have one. I mean possibly the most fault tolerent would be raid 0+1 but i could be wrong and RAID 5 is considered true raid as u can in some setups lose more than one drive, or if u have hot swaps available then it will rebuild itself if its a very clever controller e.g. in a SAN or similar. What would you say is the best RAID for redundancy and mass storage e.g. lose a drive but no lose of data and say 900GB + of storage spaceFor 1Tb you've really got 2 options:
RAID10/0+1 with 4x500Gb disks - you could do this with an onboard controller but I'm not sure what the performance is like. I tried nVidia RAID1 at one point and wasn't impressed with the write speed, it would be fine for storage but you'd need something else for at least the swap file which might be tricky if you've only got 4 onboard ports.
RAID5 with 4x320Gb disks - the saving in disk cost could cover a cheap 4 port card or most of an 8 port one to leave space for expansion. Again you'd need something else to boot off but with an add in card you're not using up onboard ports.
RAID10/0+1 with 4x500Gb disks - you could do this with an onboard controller but I'm not sure what the performance is like. I tried nVidia RAID1 at one point and wasn't impressed with the write speed, it would be fine for storage but you'd need something else for at least the swap file which might be tricky if you've only got 4 onboard ports.
RAID5 with 4x320Gb disks - the saving in disk cost could cover a cheap 4 port card or most of an 8 port one to leave space for expansion. Again you'd need something else to boot off but with an add in card you're not using up onboard ports.
Nope, it's not a true hardware card. Take a look at your CPU usage while you do some intensive write operations, it'll jump up and then return to normal when the write finishes. With a true hardware card that doesn't happen.