I'm planning to buy a RAID card.
I'm only going to use RAID 0.
I'm aware of the dangers of RAID 0 but the (few) important data will be backed up very frequently.
My question is about cards with many ports. For example the 8 port LSI MegaRAID 8480E
Am I free in the way I configure such cards?
For example four 2 disc setups. Or one 4 disc setup + one 2 disc setup.
When copying data between drives/arrays on the same card does the data stay 'inside' the RAID card or does it go to and from PC memory?[/b]
RAID card
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Thanks for the welcome Andy!
It may sound stupid but I'm still not sure how much storage space I need.
Likely the drives availble will 'force' me to a certain amount of storage.
My current setup is just enough. Or likely to little because HDs that are close to 100% filled suffer a performance drop.
Currently I have:
- 1x Western Digital Raptor WD740GD ->74GB system drive
- 1x Western Digital Raptor WD740GD ->74GB work drive
- 1x Samsung HD501LJ -> 500GB storage
- 1x Western Digital WD3200JB -> 500GB storage
- Asus P5K motherboard. Has RAID support.
Currently I don't use RAID.
The Raptors are first generation. So nearly 5 years old. They still function but sometimes... hard to explain but lets just say that my feeling tells me they are near to dying.
-------------------------
The reason I want RAID
My motherboard has only 4 SATA connectors. That's to few for practical use. So I can either buy another motherboard or some card I can also use in my next motherboard.
Of course I like the speed too
Why such a long winded answer for a simple 'how much space' question?
I don't really need much space on my system drive. But the fastest drive I can find happens to be VelociRaptor 300GB
http://westerndigital.com/en/products/P ... riveID=494
But I need 2 of them if I want to use a RAID setup. A that's a bit expensive...
The other drives I described as storage... well that is a but of a lie.
They are for storage but I'm one of those do everything at once type of person. So I'm downloading (usenet), RARing, encoding, and some otehr stuff all at the same time. And basicly due to the system and work drive being to small I use the storage drive as work drives too.
I'm prepared to replace all drives. As I wrote in my 1st post I do make backups. Every important piece of data is backuped daily or hourly with 3rd part software (AISbackup) over my network.
I only trust network backups since my motherboard broke down and killed all my drives. Anyway the network-backup-drives get replaced monthly. So backly I have several older drives in my cupboard with backups. I could use the storage drives for that.
For storage/work drives I'm now concidering Western Digital Caviar Black 1TB drives. http://westerndigital.com/en/products/p ... riveid=488
2 of those drives would be enough for my total storage need.
http://westerndigital.com/en/products/p ... riveid=488
The transfer speed of the Caviars is good (especially in RAID)
The Raptors have a far superior access time. And thats of great importance for the responsiveness of the PC.
Show me smaller drives with similar speeds of VelociRaptor and I will seriously consider them.
As I wrote above the VelociRaptor are expensive so likely I only will buy 1 of them (unless conviced otherwise...)
How would a single VelociRaptor hold up against a RAID-0 Caviar Black?
I know access time won't improve in RAID but the added throughput of the RAID-0 brings overall reponsiveness closer to that of a single VelociRaptor.
That said many things work faster if they can use a seconddisc as a work disc. And that would reduce the effectiveness of one big RAID disc.
It would be nice if I could use the old Raptors in RAID-0 as long a s they keep working.
I want the RAID card to be a little future proof; as far as that is possible with PCs.
So I think PCI-e is the only choice then.
Future proof also means the system may hold more than 2TB lateron that's (far) less likely.
And last... perhaps another motherboard will be a better solution?
Thanks for reading this far
It may sound stupid but I'm still not sure how much storage space I need.
Likely the drives availble will 'force' me to a certain amount of storage.
My current setup is just enough. Or likely to little because HDs that are close to 100% filled suffer a performance drop.
Currently I have:
- 1x Western Digital Raptor WD740GD ->74GB system drive
- 1x Western Digital Raptor WD740GD ->74GB work drive
- 1x Samsung HD501LJ -> 500GB storage
- 1x Western Digital WD3200JB -> 500GB storage
- Asus P5K motherboard. Has RAID support.
Currently I don't use RAID.
The Raptors are first generation. So nearly 5 years old. They still function but sometimes... hard to explain but lets just say that my feeling tells me they are near to dying.
-------------------------
The reason I want RAID
My motherboard has only 4 SATA connectors. That's to few for practical use. So I can either buy another motherboard or some card I can also use in my next motherboard.
Of course I like the speed too
Why such a long winded answer for a simple 'how much space' question?
I don't really need much space on my system drive. But the fastest drive I can find happens to be VelociRaptor 300GB
http://westerndigital.com/en/products/P ... riveID=494
But I need 2 of them if I want to use a RAID setup. A that's a bit expensive...
The other drives I described as storage... well that is a but of a lie.
They are for storage but I'm one of those do everything at once type of person. So I'm downloading (usenet), RARing, encoding, and some otehr stuff all at the same time. And basicly due to the system and work drive being to small I use the storage drive as work drives too.
I'm prepared to replace all drives. As I wrote in my 1st post I do make backups. Every important piece of data is backuped daily or hourly with 3rd part software (AISbackup) over my network.
I only trust network backups since my motherboard broke down and killed all my drives. Anyway the network-backup-drives get replaced monthly. So backly I have several older drives in my cupboard with backups. I could use the storage drives for that.
For storage/work drives I'm now concidering Western Digital Caviar Black 1TB drives. http://westerndigital.com/en/products/p ... riveid=488
2 of those drives would be enough for my total storage need.
http://westerndigital.com/en/products/p ... riveid=488
The transfer speed of the Caviars is good (especially in RAID)
The Raptors have a far superior access time. And thats of great importance for the responsiveness of the PC.
Show me smaller drives with similar speeds of VelociRaptor and I will seriously consider them.
As I wrote above the VelociRaptor are expensive so likely I only will buy 1 of them (unless conviced otherwise...)
How would a single VelociRaptor hold up against a RAID-0 Caviar Black?
I know access time won't improve in RAID but the added throughput of the RAID-0 brings overall reponsiveness closer to that of a single VelociRaptor.
That said many things work faster if they can use a seconddisc as a work disc. And that would reduce the effectiveness of one big RAID disc.
It would be nice if I could use the old Raptors in RAID-0 as long a s they keep working.
I want the RAID card to be a little future proof; as far as that is possible with PCs.
So I think PCI-e is the only choice then.
Future proof also means the system may hold more than 2TB lateron that's (far) less likely.
And last... perhaps another motherboard will be a better solution?
Thanks for reading this far
Well your question really sounds like "storage vs performance vs cost", that could rule out going to rule out a proper RAID card with cache and blazing performance. But you could look into something like the following for your storage. As its a seperate card and PCIe 1x it is very future-proofed, but spending that amount of money for something that you dont need seems pointless (i.e. RAID-5).
http://www.scan.co.uk/Product.aspx?WebProductId=884875
You could just get a new mobo, many newer mid-range and high-end boards have 6, 8, and 10 SATA ports (above 6 is usually through a secondary chip), and some chipsets have poor/terrible performance, so if you are looking that way, ask first.
The Velociraptor is now available in a 150GB model, not sure about its performance, it should be within 2% of its big brother, also they are very high-pitched (read the SPCR review). SSD's are a no-no for you as you have mentioned cost.
How much RAM have you got.? and do you have a page file, that alone could make a big performance difference when you are running many drive heavy programs.
Andy
http://www.scan.co.uk/Product.aspx?WebProductId=884875
You could just get a new mobo, many newer mid-range and high-end boards have 6, 8, and 10 SATA ports (above 6 is usually through a secondary chip), and some chipsets have poor/terrible performance, so if you are looking that way, ask first.
The Velociraptor is now available in a 150GB model, not sure about its performance, it should be within 2% of its big brother, also they are very high-pitched (read the SPCR review). SSD's are a no-no for you as you have mentioned cost.
How much RAM have you got.? and do you have a page file, that alone could make a big performance difference when you are running many drive heavy programs.
Andy
All cheap raid cards, like the highpoint raids, and motherboard raid, are using the cpu to do the "thinking work". Those raid controllers don't have their own memory and aren't intelligent at all.
Seen from that perspective the raid on your motherboard will perform more or less similar, performance wise compared to cheap raid controllers.
The raid system is as fast as the slowest drive, or the controller. Raid 0 will only increase the data throughput, and will give a seek-time penalty, dependent on the speed of the raid controller.
1 thing to consider, a raid 0 will fail every year, some people calculated statistics about it, but I can't find the source anymore. Also if your controller fails, the raid is inaccessible until you get a similar controller. If you are using motherboard-raid, and the motherboard fails, you will need a similar motherboard to access your raid again.
The raid card you are suggesting, the LSI-Megaraid is a highend card, also capable of raid-5. This are "intelligent controllers" with their own processors, memory etc. They are also really expensive.
If you are going to pay for such an expensive controller why not use it's features and processing power and go for raid 5. Your data is a lot safer and random io and doing several things at the same time is something those raids are built for.
However raid 5 won't beat raid 0 performance wise.
A comparison of a couple of expensive raid controllers used in combination with raid 0 , 1 and 5 can be found at this article at tomshardware.
If you are only going to use raid 0, an expensive raid controller made for raid 5 will be overkill. Highpoint has also nice controllers with a lot of connectors and are a lot cheaper. When used in raid 0 they are also performing quite good, I think they are worth considering also, in this specific scenario. Although these type of controllers are using your cpu for some calculations, in raid 0 these calculations are so minimal that it isn't worth buying a really expensive controller for it.
I hope this helps you,
Seen from that perspective the raid on your motherboard will perform more or less similar, performance wise compared to cheap raid controllers.
The raid system is as fast as the slowest drive, or the controller. Raid 0 will only increase the data throughput, and will give a seek-time penalty, dependent on the speed of the raid controller.
1 thing to consider, a raid 0 will fail every year, some people calculated statistics about it, but I can't find the source anymore. Also if your controller fails, the raid is inaccessible until you get a similar controller. If you are using motherboard-raid, and the motherboard fails, you will need a similar motherboard to access your raid again.
The raid card you are suggesting, the LSI-Megaraid is a highend card, also capable of raid-5. This are "intelligent controllers" with their own processors, memory etc. They are also really expensive.
If you are going to pay for such an expensive controller why not use it's features and processing power and go for raid 5. Your data is a lot safer and random io and doing several things at the same time is something those raids are built for.
However raid 5 won't beat raid 0 performance wise.
A comparison of a couple of expensive raid controllers used in combination with raid 0 , 1 and 5 can be found at this article at tomshardware.
If you are only going to use raid 0, an expensive raid controller made for raid 5 will be overkill. Highpoint has also nice controllers with a lot of connectors and are a lot cheaper. When used in raid 0 they are also performing quite good, I think they are worth considering also, in this specific scenario. Although these type of controllers are using your cpu for some calculations, in raid 0 these calculations are so minimal that it isn't worth buying a really expensive controller for it.
I hope this helps you,
Andy,
Yes cost is piece of the puzzle too. How much extra I would spend depends on the performance gain.
I've read some (re)views about RAID 0 and they are to mixed to be of any use. Some say RAID never will give any benefit in desktop work. Some claim a significant performance boost. Others claim a performance boost is only possible with an expensive card.
On top of that some say that the expensive cards are geared toward certain types of highend (intel) motherboards and giving compatibility issues with more mainstream boards.
Lets say I want to spend $3 per percent performance gain
The 150GB model isn't availble here (yet)
Currently I have no swapfile.
I have 4GB dual channel ram. (Balistix)
The RAMdisk I have is the performance I'm looking for...
1.5GByte/s 0ms access time.
---------------------------
http://www.memorysuppliers.com/25suta35inso.html
Speed is below mainstream drives. Of course the access time is better.
http://www.anandtech.com/storage/showdo ... i=2982&p=4
Read the user comments. Kinda scary.
Yes cost is piece of the puzzle too. How much extra I would spend depends on the performance gain.
I've read some (re)views about RAID 0 and they are to mixed to be of any use. Some say RAID never will give any benefit in desktop work. Some claim a significant performance boost. Others claim a performance boost is only possible with an expensive card.
On top of that some say that the expensive cards are geared toward certain types of highend (intel) motherboards and giving compatibility issues with more mainstream boards.
Lets say I want to spend $3 per percent performance gain
The 150GB model isn't availble here (yet)
Currently I have no swapfile.
I have 4GB dual channel ram. (Balistix)
The RAMdisk I have is the performance I'm looking for...
1.5GByte/s 0ms access time.
---------------------------
http://www.memorysuppliers.com/25suta35inso.html
Speed is below mainstream drives. Of course the access time is better.
http://www.anandtech.com/storage/showdo ... i=2982&p=4
Read the user comments. Kinda scary.
Last edited by Mute on Sat Oct 18, 2008 10:34 am, edited 3 times in total.
sjoukew,
The suggested card was merely suggested because I found one for Euro 230 and thought it was a good deal. But if most of the cost is in the RAID-5 part of the controler is possibly is lots of overkill.
The failurerate you mentioned is much higher as I would have guessed
I make regular backups but needless to say I find a crashed system very irritating.
Going to reads the article at THG now.
The suggested card was merely suggested because I found one for Euro 230 and thought it was a good deal. But if most of the cost is in the RAID-5 part of the controler is possibly is lots of overkill.
The failurerate you mentioned is much higher as I would have guessed
I make regular backups but needless to say I find a crashed system very irritating.
Going to reads the article at THG now.
RAID is not really about boosting performance. It's about providing redundancy in the storage subsystem to help protect data against hardware failure.
RAID 5, while an excellent medium is usually overkill for msot desktops unless they are dealing with large amounts of data or particualrly large files. For most desktop use, RAID 1 is sufficient to provide a reasonably cost effective safety net against drive failure.
For maximum safety net you'll likely be looking at a controller that can do RAID 10 (note not 0+1/1+0), RAID 6 or RAID 50 but you are starting to get into pricey controllers (at least $500 without BBU).
Probably the most cost effective, reliable and well performing solution I've come across are the cards form 3Ware. They are available in a number of interfaces, modes supported drives supported and price points.
As for RAID 0, it may provide a slight performance boost (typically from my experience <5-10%).but it also doubles your risk of data loss,
RAID 5, while an excellent medium is usually overkill for msot desktops unless they are dealing with large amounts of data or particualrly large files. For most desktop use, RAID 1 is sufficient to provide a reasonably cost effective safety net against drive failure.
For maximum safety net you'll likely be looking at a controller that can do RAID 10 (note not 0+1/1+0), RAID 6 or RAID 50 but you are starting to get into pricey controllers (at least $500 without BBU).
Probably the most cost effective, reliable and well performing solution I've come across are the cards form 3Ware. They are available in a number of interfaces, modes supported drives supported and price points.
As for RAID 0, it may provide a slight performance boost (typically from my experience <5-10%).but it also doubles your risk of data loss,
-
xan_user
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RAID works great for servers so they aren't down when a drive fails, and you can hot swap a replacement in.
At home its like 5 mins of down time if a drive fails, just pop in the BU image and reboot. (OK 5 mins plus the time to copy BU image to a new drive for new BU.But you can do that in the background.)
I learned this the hard way, after losing a raid card and all the data.
If you go raid, I please take my suggestion and back up all important data from raid aray to a remote or detachable drive just in case.
At home its like 5 mins of down time if a drive fails, just pop in the BU image and reboot. (OK 5 mins plus the time to copy BU image to a new drive for new BU.But you can do that in the background.)
I learned this the hard way, after losing a raid card and all the data.
If you go raid, I please take my suggestion and back up all important data from raid aray to a remote or detachable drive just in case.
xan_user,
I'm doing what you suggested for quite a while.
Once something went really wrong in my PC and several HD crashed.
There was even real smoke. I'm still not sure what happend but it's proof enough for me that RAID isn't safe enough.
I need quite a lot of discspace for computing but most of my data isn't of much value. It can easily be regenerated/downloaded/reinstalled.
Only a fairly small amount of my data is inreplaceble. I have a LAN. The important data is backuped daily (if changed). The very important data is backedup every hour (if changed). The hourly backups are rather small. Usually no more than 10MB uncompressed. I keep many generations of that hourly data so I can even go 'back in time'
Something not possible with RAID.
Once in a while I swap the backup disc with another one. I have 3 backup discs. For my personal use this is an (almost) perfect setup. Even if I ever would go for RAID 5 I would keep using it.
Besides of that most problems don't come from crashed HDs but accidently deleted files, Windows unable to boot, etc
All things where RAID won't be of help.
That's why I stated at the very beginning I use other ways to backup my data. I just knew people would post warnings about backups. And they are right about that. Same goes for every setup BTW.
But performancewise, where this thread is about, it's no issue.
If RAID-0 doubles performance RAID-5 will do the same*. If RAID-0 doesn't improve performance RAID-5 won't either.
*= with powerfull enough cards.
I'm doing what you suggested for quite a while.
Once something went really wrong in my PC and several HD crashed.
There was even real smoke. I'm still not sure what happend but it's proof enough for me that RAID isn't safe enough.
I need quite a lot of discspace for computing but most of my data isn't of much value. It can easily be regenerated/downloaded/reinstalled.
Only a fairly small amount of my data is inreplaceble. I have a LAN. The important data is backuped daily (if changed). The very important data is backedup every hour (if changed). The hourly backups are rather small. Usually no more than 10MB uncompressed. I keep many generations of that hourly data so I can even go 'back in time'
Something not possible with RAID.
Once in a while I swap the backup disc with another one. I have 3 backup discs. For my personal use this is an (almost) perfect setup. Even if I ever would go for RAID 5 I would keep using it.
Besides of that most problems don't come from crashed HDs but accidently deleted files, Windows unable to boot, etc
All things where RAID won't be of help.
That's why I stated at the very beginning I use other ways to backup my data. I just knew people would post warnings about backups. And they are right about that. Same goes for every setup BTW.
But performancewise, where this thread is about, it's no issue.
If RAID-0 doubles performance RAID-5 will do the same*. If RAID-0 doesn't improve performance RAID-5 won't either.
*= with powerfull enough cards.
What kind of disk access you need?
If mostly sequential reads of big blocks, then any RAID (esp RAID0) will improve performance.
If mostly sequential writes of big blocks, then RAID0 is way to go.
If mostly random seeks and reads of short blocks, then no RAID on ordinary 7k2RPM drives can beat Velociraptor - but using fast (15kRPM) SAS drives [any RAID or not] will improve performace.
If mostly random seeks and writes of short blocks, then no RAID on ordinary 7k2RPM drives can beat Velociraptor - but RAID0/10 setups with 15kRPM SAS drives may improve performance.
Using good dedicated controller with lot of memory, fast processor and battery backup may improve RAID5/6 write speeds too, but usually RAID5/6 write speeds are lower than for single drive. And because you actually don't need reduntancy, then RAID1/10/5/50/6/60 solutions are not needed anyway.
Shortly - depend on your required disk access pattern you need to choose between Velociraptors, expensive controller with ordinary SATA drives or cheap controller with expensive SAS drives
Oh, and I forgot about multiple data streams. If your application does access data in multiple streams (desktop applications usually don't), then usually good RAID controlles improves performance with any RAID configuration.
--
Previous claims are not facts, but only my humble opinion, based on various online information and on personal tests with onboard RAID. I've not tested many RAID scenarios, so I haven't had expensive RAID controller nor fast SAS drives in hand to test their performance.
If mostly sequential reads of big blocks, then any RAID (esp RAID0) will improve performance.
If mostly sequential writes of big blocks, then RAID0 is way to go.
If mostly random seeks and reads of short blocks, then no RAID on ordinary 7k2RPM drives can beat Velociraptor - but using fast (15kRPM) SAS drives [any RAID or not] will improve performace.
If mostly random seeks and writes of short blocks, then no RAID on ordinary 7k2RPM drives can beat Velociraptor - but RAID0/10 setups with 15kRPM SAS drives may improve performance.
Using good dedicated controller with lot of memory, fast processor and battery backup may improve RAID5/6 write speeds too, but usually RAID5/6 write speeds are lower than for single drive. And because you actually don't need reduntancy, then RAID1/10/5/50/6/60 solutions are not needed anyway.
Shortly - depend on your required disk access pattern you need to choose between Velociraptors, expensive controller with ordinary SATA drives or cheap controller with expensive SAS drives
Oh, and I forgot about multiple data streams. If your application does access data in multiple streams (desktop applications usually don't), then usually good RAID controlles improves performance with any RAID configuration.
--
Previous claims are not facts, but only my humble opinion, based on various online information and on personal tests with onboard RAID. I've not tested many RAID scenarios, so I haven't had expensive RAID controller nor fast SAS drives in hand to test their performance.
Sounds to me like a Raptor would be in order, and a nice fast 7200rpm drive as well, a Samsung 1TB, 640GB or 320GB would seem ideal, or the WD equivilent.
Drop the idea of the RAID, as you wont get as much of a performance boost as you are hoping for without it costing a mint.
If you want that kind of performance boost, and dont have loads of data (that you need really fast access to) then you would be best of getting a 64GB SSD and again a mainstream 7200rpm drive to do your donkey work/take the load away from your main drive.
Andy
Drop the idea of the RAID, as you wont get as much of a performance boost as you are hoping for without it costing a mint.
If you want that kind of performance boost, and dont have loads of data (that you need really fast access to) then you would be best of getting a 64GB SSD and again a mainstream 7200rpm drive to do your donkey work/take the load away from your main drive.
Andy
Well, that's because whilst continuous read/write speed is likely increased, so is the latency. Depnding on what applications you use, you will see a boost or slightly reduced performance.Mute wrote:I've read some (re)views about RAID 0 and they are to mixed to be of any use. Some say RAID never will give any benefit in desktop work. Some claim a significant performance boost. Others claim a performance boost is only possible with an expensive card.
I've also read that those HostRAID adapters on motherboards aren't any better in performance than a complete software raid.
edit: I just see Arvo already gave a comprehensive reply.