Configuring RAID on Linux

Continued from page: 1

Saturday, August 09, 2003

Hardware used

We used the following hardware configuration for our RAID setup.

Four Seagate 40 GB Parallel ATA drives

Two Maxtor 120 GB Serial ATA drives

Intel 875PBZ motherboard, having two Serial ATA channels in addition to the Parallel ATA ones

512 MB dual-channel DDR 400 RAM

Intel P4 3.0 GHz processor

Onboard Gigabit Ethernet

The size of a RAID volume depends on the size of the smallest partition taking part in the array. If ‘S’ is the size of the smallest partition and we have ‘N’ partitions of the same size as the smallest partition or more than it, the size of the array will be S*(N-1). So, keep all partitions in the array of same size, otherwise you will waste space in bigger partitions. We had four 40 GB disks and two 120 GB disks, so we made 40 GB partitions on each, which were part of the array. The remaining 80 GB on each 120 GB disk was formatted as a separate partition. These partitions were not a part of the array, and were, therefore, used for storing other data. Theoretically, you can have multiple partitions from the same hard drive forming the RAID array on Linux. Technically, however, this is not a good idea as the hard drive could crash and bring down the array.

For more on RAID, see More Reliability with RAID at www.pcquest.com/content/server_ side/101061801.asp or on this month’s PCQEssential CD (system\cdrom\hotutils\utils\Article detail.htm).

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