speed of serial ATA drives? at DVinfo.net

Matthew de Jongh · December 10th, 2003, 07:55 AM

Hello.

i added a bunch of SATA drives to my system.

i had just one SATA drive a 250 gig, on the motherboards SATA controller but i was needing more space and worried about how to back it up.

so i put in an adaptec serial ata raid controller (2410sa)

so now i have a raid 5 with (3) 250 gig drives, all of the same make/model etc.

the primary reason for doing this was redundancy and fault tolerance, but i was anticipating a bit of a jump in the drive speed, first off because of the SATA speed, plus doign the raid 5 usually bumps up the speed because you have the tasks spread over so many drives.

i have a basic utility for checking the read and write speeds that came with my canopus dv capture card and it tells me that my regular ide drive does 35mb/sec read and 26mb/sec write

but it says that the sata raid is doing 20mb/sec read and 27mb/sec write.

i don't get it. at the very least the serial ata should be faster shouldn't it??

matthew

Don Blish · December 12th, 2003, 07:21 PM

From long time experience using RAID 5 in database servers, I can say that, generally RAID 5 does not increase write throughput over that on a single naked drive. This is because the data is being written to one drive and the redundant data is being written to at least one of the others. With 5 - 7 drives and multiple users, the overall write bandwith is indeed higher, but of course, video writes are inherently "single threaded".

The higher throughput you are recalling is from, so called RAID 0, which is really not a redundant RAID setting at all but is another way of saying "striping". In that mode odd numbered blocks go to one drive and even to another so you really do get double throughput.....but no disaster protection.

The upshot is that 3 drives is barely adequate for RAID 5 since losing just one drive leaves you "critical". You may see an improvement adding another drive. I know the cost is modest but the space and power needed may be an issue in your case.

John Britt · December 12th, 2003, 08:03 PM

Do a google search on SATA performance and speed -- the reviews I've read mostly seem to say that you *won't* get much of a speed/performance boost from SATA drives over regular ATA drives. I did a quick search and found a little comparison at techtv.com: http://www.techtv.com/screensavers/products/story/0,24330,3485251,00.html

There are more in-depth comparisons on the net that you can find....

Matthew de Jongh · December 12th, 2003, 08:08 PM

i understand the raid 0,1,5 and even 10

i have a lot of raid stuff at work and i have seen a little bit of a bump in the raid 5, not a ton but some.

i am planning on adding a fourth drive as the hot spare.

the ultimate goal is to get 5 drives for a grand total of 1000 gigabyte+ spare

just seems like a nice magic number, like mach 1

matthew

Glenn Chan · December 12th, 2003, 11:15 PM

Quote:

but it says that the sata raid is doing 20mb/sec read and 27mb/sec write.

RAID performance depends on a lot of factors. The RAID controller is a big factor, as well as drive/RAID interactions, the RAID firmware, and the program you are using to test.

Ultimately what matters is real world performance.
Can you "feel" a difference between the two? (i.e. stuff loads faster)
Does RAID render faster than just a bunch of disks?

Jesse Castro · December 13th, 2003, 08:11 AM

Matthew,

I noticed you mentioned that you installed a PCI SATA control card. I'm guessing that your speed decrease is due in part to haveing to go through the PCI bus which could be littered with other operations such as sound cards, network cards, and what other cards you might have plugged into a PCI slot. When it comes to using SATA drives there's only one drive out there that can use up most of the bus bandwidth that SATA has to offer and that drive has only 36GB on it. Otherwise going SATA drives are about on par with normal IDE drives. I wouldn't rely to heavily on that read/ write program you have instead try using the RAID config in real world testing and see if it really bothers you using it. If it doesn't then let things be, if it does then you might have to do some more tweaking with your RAID config.

Jess

December 10th, 2003, 07:55 AM	#1
Matthew de Jongh Major Player Join Date: Sep 2003 Location: sounthern maine Posts: 344	speed of serial ATA drives? Hello. i added a bunch of SATA drives to my system. i had just one SATA drive a 250 gig, on the motherboards SATA controller but i was needing more space and worried about how to back it up. so i put in an adaptec serial ata raid controller (2410sa) so now i have a raid 5 with (3) 250 gig drives, all of the same make/model etc. the primary reason for doing this was redundancy and fault tolerance, but i was anticipating a bit of a jump in the drive speed, first off because of the SATA speed, plus doign the raid 5 usually bumps up the speed because you have the tasks spread over so many drives. i have a basic utility for checking the read and write speeds that came with my canopus dv capture card and it tells me that my regular ide drive does 35mb/sec read and 26mb/sec write but it says that the sata raid is doing 20mb/sec read and 27mb/sec write. i don't get it. at the very least the serial ata should be faster shouldn't it?? matthew

December 12th, 2003, 07:21 PM	#2
Don Blish Major Player Join Date: Oct 2003 Location: Portland OR Posts: 227	From long time experience using RAID 5 in database servers, I can say that, generally RAID 5 does not increase write throughput over that on a single naked drive. This is because the data is being written to one drive and the redundant data is being written to at least one of the others. With 5 - 7 drives and multiple users, the overall write bandwith is indeed higher, but of course, video writes are inherently "single threaded". The higher throughput you are recalling is from, so called RAID 0, which is really not a redundant RAID setting at all but is another way of saying "striping". In that mode odd numbered blocks go to one drive and even to another so you really do get double throughput.....but no disaster protection. The upshot is that 3 drives is barely adequate for RAID 5 since losing just one drive leaves you "critical". You may see an improvement adding another drive. I know the cost is modest but the space and power needed may be an issue in your case.

December 12th, 2003, 08:03 PM	#3
John Britt Major Player Join Date: Sep 2003 Location: Atlanta, GA Posts: 621	Do a google search on SATA performance and speed -- the reviews I've read mostly seem to say that you won't get much of a speed/performance boost from SATA drives over regular ATA drives. I did a quick search and found a little comparison at techtv.com: http://www.techtv.com/screensavers/products/story/0,24330,3485251,00.html There are more in-depth comparisons on the net that you can find....

December 12th, 2003, 08:08 PM	#4
Matthew de Jongh Major Player Join Date: Sep 2003 Location: sounthern maine Posts: 344	i understand the raid 0,1,5 and even 10 i have a lot of raid stuff at work and i have seen a little bit of a bump in the raid 5, not a ton but some. i am planning on adding a fourth drive as the hot spare. the ultimate goal is to get 5 drives for a grand total of 1000 gigabyte+ spare just seems like a nice magic number, like mach 1 matthew

December 13th, 2003, 08:11 AM	#6
Jesse Castro New Boot Join Date: Dec 2003 Location: Agat, Guam Posts: 6	Matthew, I noticed you mentioned that you installed a PCI SATA control card. I'm guessing that your speed decrease is due in part to haveing to go through the PCI bus which could be littered with other operations such as sound cards, network cards, and what other cards you might have plugged into a PCI slot. When it comes to using SATA drives there's only one drive out there that can use up most of the bus bandwidth that SATA has to offer and that drive has only 36GB on it. Otherwise going SATA drives are about on par with normal IDE drives. I wouldn't rely to heavily on that read/ write program you have instead try using the RAID config in real world testing and see if it really bothers you using it. If it doesn't then let things be, if it does then you might have to do some more tweaking with your RAID config. Jess