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Hi JD, |
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They are all different questions: |
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* Hardware RAID vs Software RAID |
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Hardware RAID offers more performance and often more sophisticated |
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RAID features. |
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Basically you're offloading the work for the RAID setup to an |
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external piece of hardware (the controller) instead of your own |
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server. Depending on how much performance you need it's well worth |
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the money. Another advantage is that Hardware RAID controllers often |
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offer you the opportunity to extend your RAID array beyond the usual |
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4 SATA interfaces. Depends on the card though. |
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* RAID levels and redundancy |
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RAID comes in different levels which offer different levels of |
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redundancy, RAID0, RAID1, RAID5, RAID6, RAID05 & RAID50. RAID0 offers |
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NO redundancy. If one of your drives fails you lose all your data on |
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that RAID. Excellent performance though. RAID1 does mirroring, cuts |
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your storage capacity in half but the redundancy is good. RAID5 is a |
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combination of both. |
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I'm currently building a 24 disk RAID array. If neccesary I could set |
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it up to allow for 8 disk-failures without losing any data and |
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without sacrificing half my storage capacity. |
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In this case I'm optimizing for performance and storage with some |
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redundancy, giving me a 9Tb storage capacity with a 4 drive failure |
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redundancy. |
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It largely depends on what you want/need and how you configure it. |
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Make sure you understand the options otherwise the redundancy you |
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thought you had will come around and bite you :-) |
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Keep in mind in building your array that the capacity is usually |
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determined by the smallest disk in the array. Buy equal size disks as |
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large as you can afford. |
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Also the performance is determined by the paths to your disks, if all |
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data has to flow through a single path (your 1 channel SATA |
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controller) you might find the controller limiting your performance |
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instead of your disks. When going for software raid get a more |
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expensive motherboard with two SATA channels to your disks. |
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* Resizing partitions & moving arrays |
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In either case you can move your array from one server to another, as |
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long as you move the entire array including the controller / software |
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raid setup. |
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Resizing partitions is a different question that has fairly little to |
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do with RAID. Higher end controllers allow you to expand arrays by |
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adding disks. If you're looking for resizable partitions over |
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multiple disks you want to have a look at LVM2. You can (and I have) |
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combine LVM with RAID but it's not strictly necessary. |
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As soon as I reach my work-laptop I can drop some links to raid array |
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configuration choices & LVM setups if you'd like. |
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Regards, |
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|
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Ramon |
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-- |
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If to err is human, I'm most certainly human. |
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-- |
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gentoo-server@g.o mailing list |
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