Is data=journal on a separate device on Ext4 as good as using a RAID controller with battery backed cache for file system consistency?

Posted by Jeff Strunk on Server Fault See other posts from Server Fault or by Jeff Strunk
Published on 2011-01-03T22:40:07Z Indexed on 2011/01/03 22:55 UTC
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linux

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raid

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storage

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ext4

It seems to me that data=journal prevents file system inconsistency in the case of power failure. Using it with a dedicated journal device mitigates the performance penalty of writing the data twice. A power outage would still lose the data that is currently being written to the journal, but the file system on disk would always be consistent.

If that amount of loss is acceptable, is a RAID controller with battery backed cache really worthwhile?

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