On 31/03/2010 17:31, Bob Friesenhahn wrote:
On Wed, 31 Mar 2010, Edward Ned Harvey wrote:
Would your users be concerned if there was a possibility that
after extracting a 50 MB tarball that files are incomplete, whole
subdirectories are missing, or file permissions are incorrect?
Correction: "Would your users be concerned if there was a
possibility that
after extracting a 50MB tarball *and having a server crash* then
files could
be corrupted as described above."
If you disable the ZIL, the filesystem still stays correct in RAM,
and the
only way you lose any data such as you've described, is to have an
ungraceful power down or reboot.
Yes, of course. Suppose that you are a system administrator. The
server spontaneously reboots. A corporate VP (CFO) comes to you and
says that he had just saved the critical presentation to be given to
the board of the company (and all shareholders) later that day, and
now it is gone due to your spontaneous server reboot. Due to a
delayed financial statement, the corporate stock plummets. What are
you to do? Do you expect that your employment will continue?
Reliable NFS synchronous writes are good for the system administrators.
well, it really depends on your environment.
There is place for Oracle database and there is place for MySQL, then
you don't really need to cluster everything and then there are
environments where disabling ZIL is perfectly acceptablt.
One of such cases is that you need to re-import a database or recover
lots of files over NFS - your service is down and disabling ZIL makes a
recovery MUCH faster. Then there are cases when leaving the ZIL disabled
is acceptable as well.
--
Robert Milkowski
http://milek.blogspot.com
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