RAID 1 & Multitasking

[Phenom]

Please read title, thank you.

 

[damian24]

Does RAID improve multitasking performance and I/O/second ??????


for the correct answer u will win 1 Million Pand

depends on if the controller supports it, the soft controllers (read intel desktop chipsets) know nothing about optimising read performance and wirte would neccesarily be a little slower as there are two io operations taking place.

in terms of hardware raid 1, some have better read performance as a result of parming reads off to the different mirrors, write performance is about the same... unless like on the intel SRCSAS18E you buy a 256mb battery backup ram module (the card runs around 8k and the battery memory around 3k with a lifetime of around 2 to three years) if this is the case the raid writes become blindingly fast (for samller writes, sustained give the normal disk average throughput) as it's going to the battery cache with the controller writing it later as it's in write-back mode.

does it work... well I think it does and invested in three of the things, other may have different views.

D

 

[spiderz]

For speed go Raid 0, and get 2x WD raptors.

 

[Conradl]

General rule of thumb is that increasing the number of physical disks will always increase IOs (assuming you use Hardware RAID). The challenge is that there are generally four types of IO: Random Read/Write and Sequential Read/Write. Certain RAID levels offer different benefits depending on the type of IO.

There there are also different benefits for different types of IO depending on the block size. So Sequential writes using a small block size will be different to Random writes using a small block size.

So for my 1 Million Pands, IOs will be increased by using more physical disks - you may however not see any benefit depending on what you do. If your multitasking entails opening the office suite and changing between windows, then you would see little benefit once all the apps were open.

The table below does not format well


Significantly Random Significantly Sequential
Block Size Read Write Read Write
Small
(<32 KiB ) 1/10, 5, 6 1/10 1/10, 5, 6 1/10, 5
Medium
(Between 32
and 256 KiB) 1/10, 5, 6 1/10 1/10, 5, 6 5
Large
(>256 KiB) 1/10, 5, 6 1/10 1/10, 5, 6 5