Software RAID doesn't have a battery backed cache, tho I'd tend to marginalize your mode of failure... and it really should be one of those "never happen" cases... Yeah - that'll save you perhaps a transaction - but who's to say what's in the memory buffer is any cleaner than when the power went out? Your file system is *NOT* going to be any cleaner, you're just going to have a little more data before the PCI failure. A trivial benefit. Afterall, at least when you're dealing with software RAID, the filesystem is completely aware of it's state (sequence number), the battery backed cache is clueless, it could actually TRASH the filesystem with a bad write or the OS commits bad data because it's knowledge of that state of the disk is misrepresented/incorrect.
Hmm, that cache isn't so good.
Then again, hardware write caches have NEVER been a good thing in context of a server. (on the most part)
So - probably, you're wrong about this too. |
