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RAID 0 = Striping
RAID 1 = Mirroring
0 => 2 x 40GB wordt 80GB
1 => 2 x 40GB blijft 40GB
0 => Snelle schijf...
1 => Veilig, data wordt 2x bewaard...
TYPO!!!!!!!!! thnx martijn02
RAID 1 = Mirroring
0 => 2 x 40GB wordt 80GB
1 => 2 x 40GB blijft 40GB
0 => Snelle schijf...
1 => Veilig, data wordt 2x bewaard...
TYPO!!!!!!!!! thnx martijn02
In de search ''raid guide'' intypen levert toch echt bij de tweede posting een 100% hit of niet dan? 
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De username van de oorspronkelijke plaatser van deze posting is bij Big Crash 3 eind mei 2001 verloren gegaan. Om toch de posting zelf terug te kunnen plaatsen is de user BC3 Victim in het leven geroepen
Hier kan je ook veel vinden bijvoorbeeld.
http://howto.tucows.com/LDP/HOWTO/Software-RAID-HOWTO-2.html#ss2.3
Even een quote:
http://howto.tucows.com/LDP/HOWTO/Software-RAID-HOWTO-2.html#ss2.3
Even een quote:
Linear mode
Two or more disks are combined into one physical device. The disks are ``appended'''' to each other, so writing to the RAID device will fill up disk 0 first, then disk 1 and so on. The disks does not have to be of the same size. In fact, size doesn''t matter at all here
There is no redundancy in this level. If one disk crashes you will most probably lose all your data. You can however be lucky to recover some data, since the filesystem will just be missing one large consecutive chunk of data.
The read and write performance will not increase for single reads/writes. But if several users use the device, you may be lucky that one user effectively is using the first disk, and the other user is accessing files which happen to reside on the second disk. If that happens, you will see a performance gain.
RAID-0
Also called ``stripe'''' mode. Like linear mode, except that reads and writes are done in parallel to the devices. The devices should have approximately the same size. Since all access is done in parallel, the devices fill up equally. If one device is much larger than the other devices, that extra space is still utilized in the RAID device, but you will be accessing this larger disk alone, during writes in the high end of your RAID device. This of course hurts performance.
Like linear, there''s no redundancy in this level either. Unlike linear mode, you will not be able to rescue any data if a drive fails. If you remove a drive from a RAID-0 set, the RAID device will not just miss one consecutive block of data, it will be filled with small holes all over the device. e2fsck will probably not be able to recover much from such a device.
The read and write performance will increase, because reads and writes are done in parallel on the devices. This is usually the main reason for running RAID-0. If the busses to the disks are fast enough, you can get very close to N*P MB/sec.
RAID-1
This is the first mode which actually has redundancy. RAID-1 can be used on two or more disks with zero or more spare-disks. This mode maintains an exact mirror of the information on one disk on the other disk(s). Of Course, the disks must be of equal size. If one disk is larger than another, your RAID device will be the size of the smallest disk.
If up to N-1 disks are removed (or crashes), all data are still intact. If there are spare disks available, and if the system (eg. SCSI drivers or IDE chipset etc.) survived the crash, reconstruction of the mirror will immediately begin on one of the spare disks, after detection of the drive fault.
Write performance is the slightly worse than on a single device, because identical copies of the data written must be sent to every disk in the array. Read performance is usually pretty bad because of an oversimplified read-balancing strategy in the RAID code. However, there has been implemented a much improved read-balancing strategy, which might be available for the Linux-2.2 RAID patches (ask on the linux-kernel list), and which will most likely be in the standard 2.4 kernel RAID support.
RAID-4
This RAID level is not used very often. It can be used on three or more disks. Instead of completely mirroring the information, it keeps parity information on one drive, and writes data to the other disks in a RAID-0 like way. Because one disks is reserved for parity information, the size of the array will be (N-1)*S, where S is the size of the smallest drive in the array. As in RAID-1, the disks should either be of equal size, or you will just have to accept that the S in the (N-1)*S formula above will be the size of the smallest drive in the array.
If one drive fails, the parity information can be used to reconstruct all data. If two drives fail, all data is lost.
The reason this level is not more frequently used, is because the parity information is kept on one drive. This information must be updated every time one of the other disks are written to. Thus, the parity disk will become a bottleneck, if it is not a lot faster than the other disks. However, if you just happen to have a lot of slow disks and a very fast one, this RAID level can be very useful.
RAID-5
This is perhaps the most useful RAID mode when one wishes to combine a larger number of physical disks, and still maintain some redundancy. RAID-5 can be used on three or more disks, with zero or more spare-disks. The resulting RAID-5 device size will be (N-1)*S, just like RAID-4. The big difference between RAID-5 and -4 is, that the parity information is distributed evenly among the participating drives, avoiding the bottleneck problem in RAID-4.
If one of the disks fail, all data are still intact, thanks to the parity information. If spare disks are available, reconstruction will begin immediately after the device failure. If two disks fail simultaneously, all data are lost. RAID-5 can survive one disk failure, but not two or more.
Both read and write performance usually increase, but it''s hard to predict how much.
kijk dankuwel luie mensen!!!maar wat is nou de snelste????
RAID0 toch??
dan doe ik 2x Harddisks (IDE) / IBM 40GB (Deskstar 60GXP, 7200rpm, 2MB)
met raid0.Maar is dit erg prijzig??
De username van de oorspronkelijke plaatser van deze posting is bij Big Crash 3 eind mei 2001 verloren gegaan. Om toch de posting zelf terug te kunnen plaatsen is de user BC3 Victim in het leven geroepen
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