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Raid0 is stripping.
Raid1 is mirroring.
-Raid 0 Characteristics/Advantages:
RAID 0 implements a striped disk array, the data is broken down into blocks
and each block is written to a separate disk drive
I/O performance is greatly improved by spreading the I/O load across many
channels and drives
-RAID 0 Disadvantages:
The failure of just one drive will result in all data in an array being lost
Should never be used in mission critical environments
I think trading is in this category so ...
-Raid1 Characteristics/Advantages:
One Write or two Reads possible per mirrored pair
Twice the Read transaction rate of single disks, same Write transaction
rate as single disks
100% redundancy of data means no rebuild is necessary in case of a disk
failure, just a copy to the replacement disk
Transfer rate per block is equal to that of a single disk
Under certain circumstances, RAID 1 can sustain multiple simultaneous drive
failures
Simplest RAID storage subsystem design
-Raid 1 Disadvantages:
Highest disk overhead of all RAID types (100%) - inefficient
Typically the RAID function is done by system software, loading the
CPU/Server and possibly degrading throughput at high activity levels.
Hardware implementation is strongly recommended
May not support hot swap of failed disk when implemented in "software
So configuration should be : Raid 1 (2 disks) or Raid0+1 (4 disks) and not
Raid0
Time to access disk: milli seconds
Time to access Memory: Micro seconds
Ratio: 1/1000
my 0.02
At 2001-05-20 14:29 +1000, Jon Macmichael wrote:
>Regarding the RAID query:
>
>My brother recently installed a Promise Raid Card with two of the new IBM
>dtla 20g h-drives. He doesn't trade but uses Photoshop and so on. Two things
>are most impressive with the set-up.
>
>#1. as the RAID is stripped the reading and writing from/to the h-drive was
>incredibly fast.
>
>#2. the IBM's have a quiet utility. This is adjustable via a slider. So set
>to about half it makes the drive super quiet. Set to full then the drive is
>basically inaudible.
>
>Now the problems:
>
>#1. I believe the acoustic utility uses some resources.
>
>#2. Only having the drives installed for a few weeks, and having setup w2000
>he has tried defragging and the computer locks up on the main partition.
>Evidently he's found that Microsoft are aware of some problem here!!!! Now
>he's also found that one of the drives is faulty and as it was bought OEM
>he's got problems. No warranty. To stripe, both drives need to be identical
>and his new drives have already been superceded. So with the cost of the
>RAID card plus the extra drive (MB rate up about 300%?), then, when one
>drive fails and you replace two drives, so your into an expensive exercise.
>
>Myself: with a new Dell which came with a Maxtor drive, I found they also
>have an acoustic utility which I've loaded. Currently its quieter, but yet
>to test it with the live data and any resource implications.
>
>A computer wizz has often suggested to me that hard drives are a limiting
>factor to general speed of computers.
>
>At least for me the noise of the continual reading-writing drives me nuts.
>
>Jon
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