Filesystems (ext3, reiser, xfs, jfs) comparison on Debian Etch (Debian
Posted Apr 26, 2006 6:46 UTC (Wed) by joib
In reply to: Filesystems (ext3, reiser, xfs, jfs) comparison on Debian Etch (Debian
Parent article: Filesystems (ext3, reiser, xfs, jfs) comparison on Debian Etch (Debian
keep in mind that these benifits you are listing only count if you are useing a hard drive that allows you to disable the write cache on it (i.e. no IDE drives qualify).
As was already mentioned, most IDE drives allow you to disable write-back cache. However, many manufacturers consider this operation a warranty-voiding one, since disabling write-back caching causes much more physical writes which significantly reduces the life of the drive.
if the drive can tell you that the write is completed while it's in the drives memory it's still vundrable to being lost.
since there is a huge performance penalty for doing this it's seldom done even on the drives that support it.
Fortunately, you can have your cake and eat it too. The trick is to implement IO barriers using the CACHE FLUSH and/or FUA commands. That way you can have the performance and MTBF benefits of write-back caching while still having a safe fsync() (safe as in doesn't return before data is on the platters).
Also note that the IO barrier rewrite referenced above was included only from 2.6.16+; I don't know how previous kernels did it.
to post comments)