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#1
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General RAID question
I understand the difference between the various RAID modes. What I'm trying
to find out is how big the performance hit is in using RAID 0 to mirror data. Are we talking a few ms here and there or many seconds? I guess what I really want to know is if it is a noticeable delay to the end user. Thanx, Vic Baron -- There are 10 kinds of people - those who understand binary and those who don't |
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#2
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General RAID question
hardware Raid has no such penalty. Software mirroring on the other hand
uses the CPU to perform the work. Vic Baron wrote: I understand the difference between the various RAID modes. What I'm trying to find out is how big the performance hit is in using RAID 0 to mirror data. Are we talking a few ms here and there or many seconds? I guess what I really want to know is if it is a noticeable delay to the end user. Thanx, Vic Baron |
#3
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General RAID question
Using hardware raid - no noticable performance hit
"Vic Baron" wrote in message ... I understand the difference between the various RAID modes. What I'm trying to find out is how big the performance hit is in using RAID 0 to mirror data. Are we talking a few ms here and there or many seconds? I guess what I really want to know is if it is a noticeable delay to the end user. Thanx, Vic Baron -- There are 10 kinds of people - those who understand binary and those who don't |
#4
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General RAID question
raid 0 won't give a performance HIT, it will IMPROVE performance in most
disk intensive operations: booting/launching, defragging, searching, virus/spyware scanning, backup, large file conversions. the boost in other "everyday" things is not noticable (Word won't type faster!) most raid 0 solutions today are built-in to the main chipset, and use a combination of software (in the driver) and some hardware assist (in the chipset); for the most part the "overhead" is more than made-up-for by the performance boost. but remember, if one drive in the array fails then you loose it all. so backup backup backup (good advice for non-raid 0 too!). |
#5
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General RAID question
wrote in message ... raid 0 won't give a performance HIT, it will IMPROVE performance in most disk intensive operations: booting/launching, defragging, searching, virus/spyware scanning, backup, large file conversions. the boost in other "everyday" things is not noticable (Word won't type faster!) most raid 0 solutions today are built-in to the main chipset, and use a combination of software (in the driver) and some hardware assist (in the chipset); for the most part the "overhead" is more than made-up-for by the performance boost. but remember, if one drive in the array fails then you loose it all. so backup backup backup (good advice for non-raid 0 too!). I think the OP screwed up a bit here. He referred to RAID0 as mirroring. RAID0 is *striping*, RAID1 is *mirroring*. I assume the OP actually meant mirroring. The whole purpose of RAID0 is to increase performance, so everything stated in this post above is correct, including the cautionary notes, for striping. However, since I believe the OP was actually referring to mirroring, the situation is slightly different. The performance hit for hardware mirroring is negligible. There's also so much file buffering taking place and delayed writes, it would be very difficult to even measure the differences unless you disabled these functions (which most software performance tools would do, such as SiSoftware Sandra). In fact, your read performance may increase slightly since it's theoretically possible for the raid controller to read BOTH HDs in parallel to retrieve a file. Most people use mirroring to protect data (as opposed to OS files), which is typically read far more often than written. So for most cases, there just isn't much need to worry about performance hits when it comes to hardware RAID. Of course, if you're referring to software RAID, the situation may be far different since there is no hardware assist. |
#6
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General RAID question
Thanx, Jim - you are correct - brain cramp - I was referring to RAID 1 (
mirroring ). Currently running RAID 5 ( 3 - 9G drives/15G total). Daily tape b/u. Probably going to upgrade the server and was looking at alternatives. Of course, as the saying goes"If it ain't broke, don't fix it". The R5 is working fine, probably should just leave it as is. Thanx again all, Vic "Jim" wrote in message ... wrote in message ... raid 0 won't give a performance HIT, it will IMPROVE performance in most disk intensive operations: booting/launching, defragging, searching, virus/spyware scanning, backup, large file conversions. the boost in other "everyday" things is not noticable (Word won't type faster!) most raid 0 solutions today are built-in to the main chipset, and use a combination of software (in the driver) and some hardware assist (in the chipset); for the most part the "overhead" is more than made-up-for by the performance boost. but remember, if one drive in the array fails then you loose it all. so backup backup backup (good advice for non-raid 0 too!). I think the OP screwed up a bit here. He referred to RAID0 as mirroring. RAID0 is *striping*, RAID1 is *mirroring*. I assume the OP actually meant mirroring. The whole purpose of RAID0 is to increase performance, so everything stated in this post above is correct, including the cautionary notes, for striping. However, since I believe the OP was actually referring to mirroring, the situation is slightly different. The performance hit for hardware mirroring is negligible. There's also so much file buffering taking place and delayed writes, it would be very difficult to even measure the differences unless you disabled these functions (which most software performance tools would do, such as SiSoftware Sandra). In fact, your read performance may increase slightly since it's theoretically possible for the raid controller to read BOTH HDs in parallel to retrieve a file. Most people use mirroring to protect data (as opposed to OS files), which is typically read far more often than written. So for most cases, there just isn't much need to worry about performance hits when it comes to hardware RAID. Of course, if you're referring to software RAID, the situation may be far different since there is no hardware assist. |
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