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Zoiets !
ps. volgende keer ff googlen ! dat werkt
RAID Technologies
Although there are many different implementations of RAID technologies, they all share two similar aspects. They all use multiple physical disks to distribute data, and they all store data according to a logic that is independent of the application for which they are storing data.
This article discusses three primary implementations of RAID and one subtype: RAID-0, RAID-1 (and subtype 0+1), and RAID-5. Although there are many other RAID implementations, these three types serve as an adequate representation of the overall scope of RAID solutions.
RAID-0
RAID-0 is a striped disk arrayeach disk is logically partitioned in such a way that a "stripe" runs across all the disks in the array to create a single logical partition. For example, if a file is saved to a RAID-0 array, and the application that is saving the file saves it to drive D, the RAID-0 array distributes the file across logical drive D. In this example it spans all six disks.
Figure 1 RAID-0 disk array
From a performance perspective, RAID-0 is the most efficient RAID technology because it can write to all six disks at once. When all disks store the application data, the most efficient use of the disks occurs.
The drawback to RAID-0 is its lack of reliability. If the Exchange mailbox databases are stored across a RAID-0 array and a single disk fails, you must restore the mailbox databases to a functional disk array and restore the transaction log files. In addition, if you store the transaction log files on this array and you lose a disk, you can perform only a point-in-time restore of the mailbox databases from the last backup.
RAID-1 (and 0+1)
RAID-1 is a mirrored disk array in which two disks are mirrored. When more than two disks are used, the disks are striped as well as mirrored, which is a RAID-0+1 configuration. This means that each physical disk is duplicated in the array. If you have a six-disk, RAID-0+1 array, three disks are available for data storage. In these disks, each set is striped, and each disk has a "mirror." Each time data is written to one disk, that same data is written to the mirrored disk.
Figure 2 RAID-1 disk array
RAID-1 (or 0+1) is the most reliable of the three RAID arrays because all data is mirrored after it is written. You can use only half of the storage space on the disks. Although this may seem inefficient, RAID 1 (or 0+1) is the preferred choice for data that requires the highest possible reliability.
RAID-5
RAID-5 is a striped disk array, similar to RAID-0 in the way data is distributed across the array, but RAID-5 also includes parity. This means that there is a mechanism that maintains the integrity of the data stored on the array, so that if one disk in the array fails, the data can be reconstructed from the remaining disks. Thus, RAID-5 is a reliable storage solution.
Figure 3 RAID-5 disk array
However, to maintain parity among the disks, 1/n GB of disk space is sacrificed, where n equals the number of drives in the array. For example, if you have six 9-GB disks, you have 45 GB of usable storage space. To maintain parity, one write of data is translated into two writes and two reads in the RAID-5 array; thus, overall performance is degraded.
The advantage of a RAID-5 solution is that it is reliable and uses disk space more efficiently than RAID-1 (and 1+0).
ps. volgende keer ff googlen ! dat werkt
RAID Technologies
Although there are many different implementations of RAID technologies, they all share two similar aspects. They all use multiple physical disks to distribute data, and they all store data according to a logic that is independent of the application for which they are storing data.
This article discusses three primary implementations of RAID and one subtype: RAID-0, RAID-1 (and subtype 0+1), and RAID-5. Although there are many other RAID implementations, these three types serve as an adequate representation of the overall scope of RAID solutions.
RAID-0
RAID-0 is a striped disk arrayeach disk is logically partitioned in such a way that a "stripe" runs across all the disks in the array to create a single logical partition. For example, if a file is saved to a RAID-0 array, and the application that is saving the file saves it to drive D, the RAID-0 array distributes the file across logical drive D. In this example it spans all six disks.
Figure 1 RAID-0 disk array
From a performance perspective, RAID-0 is the most efficient RAID technology because it can write to all six disks at once. When all disks store the application data, the most efficient use of the disks occurs.
The drawback to RAID-0 is its lack of reliability. If the Exchange mailbox databases are stored across a RAID-0 array and a single disk fails, you must restore the mailbox databases to a functional disk array and restore the transaction log files. In addition, if you store the transaction log files on this array and you lose a disk, you can perform only a point-in-time restore of the mailbox databases from the last backup.
RAID-1 (and 0+1)
RAID-1 is a mirrored disk array in which two disks are mirrored. When more than two disks are used, the disks are striped as well as mirrored, which is a RAID-0+1 configuration. This means that each physical disk is duplicated in the array. If you have a six-disk, RAID-0+1 array, three disks are available for data storage. In these disks, each set is striped, and each disk has a "mirror." Each time data is written to one disk, that same data is written to the mirrored disk.
Figure 2 RAID-1 disk array
RAID-1 (or 0+1) is the most reliable of the three RAID arrays because all data is mirrored after it is written. You can use only half of the storage space on the disks. Although this may seem inefficient, RAID 1 (or 0+1) is the preferred choice for data that requires the highest possible reliability.
RAID-5
RAID-5 is a striped disk array, similar to RAID-0 in the way data is distributed across the array, but RAID-5 also includes parity. This means that there is a mechanism that maintains the integrity of the data stored on the array, so that if one disk in the array fails, the data can be reconstructed from the remaining disks. Thus, RAID-5 is a reliable storage solution.
Figure 3 RAID-5 disk array
However, to maintain parity among the disks, 1/n GB of disk space is sacrificed, where n equals the number of drives in the array. For example, if you have six 9-GB disks, you have 45 GB of usable storage space. To maintain parity, one write of data is translated into two writes and two reads in the RAID-5 array; thus, overall performance is degraded.
The advantage of a RAID-5 solution is that it is reliable and uses disk space more efficiently than RAID-1 (and 1+0).
Nu in het kort: Als je een raidkey bij dell besteld krijg je voor een piekje of 400 een key, die key is niet meer dan een stukje printplaat van 1 bij 2 cm die je haaks op je moederbord kunt drukken.
Er zit ook 128mb registered geheugen bij om te bufferen. Waar 't allemaal voor is lees je hier boven
Er zit ook 128mb registered geheugen bij om te bufferen. Waar 't allemaal voor is lees je hier boven
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Met die RAID key activeer je RAID controller die standaard al in de DELL server is ingebouwd.
Zonder die key werkt de controller niet als RAID controller, maar als gewone SCSI controller.
Is schijnbaar goedkoper om het zo te produceren en er toch nog een leuk bedrag voor te vangen
Zonder die key werkt de controller niet als RAID controller, maar als gewone SCSI controller.
Is schijnbaar goedkoper om het zo te produceren en er toch nog een leuk bedrag voor te vangen
bedankt akko, eindelijk een goed en duidelijk antwoordtOp dinsdag 19 maart 2002 13:21 schreef Akko het volgende:
Met die RAID key activeer je RAID controller die standaard al in de DELL server is ingebouwd.
Zonder die key werkt de controller niet als RAID controller, maar als gewone SCSI controller.
Is schijnbaar goedkoper om het zo te produceren en er toch nog een leuk bedrag voor te vangen
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