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What is the difference between a 5 disk and a 15 disk RAID 5 array?
- Thread starter janaque
- Start date
I would like to ask what is the difference between a 5 disk and a 15 disk RAID 5 array.Is there any difference in term of performance,reliability etc?
Let deal with reliability first....
Read the entire article, especially "Why RAID 6?"
Basically raid 5 becomes more unreliable with either hard drives with greater capacity or with a greater number of drives. Raid 5, does not leave me with the warm and fuzzy feeling I used to have with the small capacities limits it had in the past. PS SCSI Backplanes limit the number of drives to 14 drives per channel, and you can not attach many u320 drives to a standard u320 cable without issues.
Performance...
A 14 drive scsi u320 raid 5, should be somewhat faster then a 5 drive array, but not dramatic, as 5 u320 scsi drives just about place the limit of data on a scsi bus (bus saturation) which the bus can handle..320 m/sec minus the scsi overhead, on a single channel raid. On a 2 (or more) channel raid, you would gain a noticeable throughput gain, as each channel adds 320 m/sec (minus overhead) to the over all throughput. That said, you would be better off with an SAS raid (PCI-E), as SAS has greater throughput in large arrays with more than 4 to 5 drives per channel (at the same drive rpm).
........................................
Chernobyl disaster..a must see pictorial
Let deal with reliability first....
Read the entire article, especially "Why RAID 6?"
Basically raid 5 becomes more unreliable with either hard drives with greater capacity or with a greater number of drives. Raid 5, does not leave me with the warm and fuzzy feeling I used to have with the small capacities limits it had in the past. PS SCSI Backplanes limit the number of drives to 14 drives per channel, and you can not attach many u320 drives to a standard u320 cable without issues.
Performance...
A 14 drive scsi u320 raid 5, should be somewhat faster then a 5 drive array, but not dramatic, as 5 u320 scsi drives just about place the limit of data on a scsi bus (bus saturation) which the bus can handle..320 m/sec minus the scsi overhead, on a single channel raid. On a 2 (or more) channel raid, you would gain a noticeable throughput gain, as each channel adds 320 m/sec (minus overhead) to the over all throughput. That said, you would be better off with an SAS raid (PCI-E), as SAS has greater throughput in large arrays with more than 4 to 5 drives per channel (at the same drive rpm).
........................................
Chernobyl disaster..a must see pictorial
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