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2008/6/9 "Todd M. Hébert" <todd@×××.ie>: |
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> We use RAID 1 on servers that are not file servers, RAID 4 or 5 on |
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> file-servers (depending on how much need for redundancy we have on a |
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Doesn't RAID 4 and 5 offer the same level of protection? I thought |
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the only difference was RAID4 had a dedicated parity device whereas |
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RAID5 stripes parity information across all devices. In either case, |
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loose two drives and the RAID is toast. |
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> We're in a data centre that isn't likely to have blackouts. (It can run on |
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> batteries for 6 hours, and has diesel generators with 48-hours worth of fuel |
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> on-site, as well as an emergency supply-chain for the diesel.) |
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I too have been in very very high profile very very nice data centers |
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with a jabillion hours of battery backup and even more of generator |
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power. One time someone hit the BIG RED BUTTON on the floor where |
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our gear was caged and presto - power was gone. Another time the city |
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cut the power mains to the building, and the generator that was |
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supposta supply half of our racks someone had left in "manual" mode as |
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apposed to automatic, thus taking out a fair number of our servers. I |
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think if you ask any sufficiently large group of people for horor |
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stories of power going out in a N+2 redundant power environmnet, |
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you'll get way more than you were looking for. |
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> I've not seen problems as described below on 3Ware cards... I believe the |
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> configuration for each RAID is is backed-up on each disk in the RAID set. |
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> I've never had a problem with those. (I have seen a problem with another |
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I too have only ever had wonderful experiences with 3Ware cards under |
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Linux. I've not had one of their cards fail, but have had backplanes |
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fail and bad cables. Diagonosing and getting your vendor to admit to |
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a bad backplane generally requires more than one outtage :( Now LSI |
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cards on the otherhand have caused me some grief. |
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> XFS filesystems no all of the above, just for reference. |
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FWIW, always have run ext3, unless it was before ext3 was 'stable', |
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then it was ext2. |
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.r' |
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