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On Sunday 10 April 2011 12:53:39 Stroller wrote: |
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> On 10/4/2011, at 8:50am, Peter Humphrey wrote: |
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> > ... |
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> > I'm just speculating at the moment, from a dabbler's point of view; what |
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> > benefits would accrue from switching from RAID-1 to RAID-5 or above? |
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> > And, in particular, what are the comparative virtues of the Samsung |
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> > disks? |
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> |
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> In your previous message you mention "adding robustness", I don't think |
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> you'd change from RAID1 in that case. |
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> |
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> RAID5 is less redundant than RAID1, but offers more space per drive. |
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> |
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> Either will continue to run if one drive fails, but RAID5 consists of more |
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> drives (each of which has the potential for failure). |
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> |
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> RAID1 has 2 disks and offers up to 1/2 redundancy. 1/2 your disks can fail |
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> without loss of data. |
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> |
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> RAID5 has X disks, where X is more than 2, and offers upto 1/X redundancy. |
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> If more than 1 drive fails then your data is toast. This inherently allows |
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> for data loss if more than only 1/3 or 1/4 (or less - 1/5 or 1/6 if you |
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> have enough drives in your system) fail. |
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> |
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> RAID6 needs an extra disk over RAID5 (at least 4 total?), and allows 2/X of |
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> them to fail whilst still maintaining data integrity. |
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> |
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> I guess that theoretically RAID6 might be more robust than RAID1 but |
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> realistically one would probably use RAID1 if the volume is intended to be |
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> a fixed size (system volume), RAID5 or RAID6 if you want to be able to |
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> easily expand the volume (add an extra drive and store more data simply by |
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> expanding the filesystem). Other kinds of RAID (10, 50 &c) may be more |
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> suitable if read or write speed is also important for specialist |
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> applications, but you say you're only interested in home workstation use, |
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> not the datacentre. |
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> |
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> Note that I only consider hardware RAID - others may be able to give advice |
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> more suited to Linux's software RAID. |
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> |
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> I use RAID5 for my TV recordings and DVD rips. There's a famous article |
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> claiming RAID5 is worthless considering the size of current hard-drives vs |
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> uncorrected error rates (which manufacturers express per million or |
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> billion bits). I'm sceptical of the article, but nevertheless I guess I'm |
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> starting to get paranoid enough I'd prefer RAID6. Unfortunately my |
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> hardware RAID controller doesn't support it, so I guess I'm saved the |
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> expense. :/ |
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|
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Useful info - many thanks! |
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|
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-- |
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Rgds |
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Peter |
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