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LWN.net Weekly Edition for May 23, 2013
An "enum" for Python 3
An unexpected perf feature
LWN.net Weekly Edition for May 16, 2013
A look at the PyPy 2.0 release
Ext3 and RAID: silent data killers?
Posted Sep 1, 2009 8:05 UTC (Tue) by drag (subscriber, #31333)
With RAID 5 the amount of time it takes to recover is so long nowadays that the chances of having a double fault is pretty good. It was one thing to have 20GB with 30MB/s performance, but it's quite another to have 1000GB with 50MB/s performance...
Posted Sep 11, 2009 1:18 UTC (Fri) by Pc5Y9sbv (guest, #41328)
My cheap MD RAID5 with three 500 GB SATA drives allows me to have 1TB and approximately 100 MB/s per drive throughput, which implies a full scan to re-add a replacement drive might take 2 hours or so (reading all 500 GB from 2 drives and writing 500 GB to the third at 75% of full speed). I have never been in a position where this I/O time was worrisome as far as a double fault hazard. Having a commodity box running degraded for several days until replacement parts are delivered is a more common consumer-level concern, which has not changed with drive sizes.
Posted Sep 3, 2009 5:05 UTC (Thu) by k8to (subscriber, #15413)
Meanwhile, you also get vastly better performance, and higher reliability of implementation.
It's really a no brainer unless you're poor.
Posted Sep 3, 2009 5:26 UTC (Thu) by dlang (✭ supporter ✭, #313)
in digging further I discovered that they key to performance was to have enough queries in flight to keep all disk heads fully occupied (one outstanding query per drive spindle), and you can do this with both raid 6 and raid 10.
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