On 07/21/2009 01:44 PM, Valerie Aurora wrote:
On Mon, Jul 20, 2009 at 10:00:50PM -0400, Theodore Tso wrote:
On Mon, Jul 20, 2009 at 07:04:03PM -0400, Valerie Aurora wrote:
I think it's extremely accurate and detailed, but too long - people's
brains turn off after about the 15th line or so. Here's an attempt to
distill your description down and refer out to another document (which
one?) for people who want to learn more.
Fair enough; I've created an external document here:
http://ext4.wiki.kernel.org/index.php/Ext3_Data%3DOrdered_vs_Data%3DWriteback_mode
Comments?
Nice!
config EXT3_DEFAULTS_TO_ORDERED
bool "Default to 'data=ordered' in ext3"
depends on EXT3_FS
help
If the mount options for an ext3 filesystem do not
include a journal mode, mount it in "data=ordered" mode.
Let me give a try at this:
The journal mode options for ext3 have different tradeoffs
between when data is guaranteed to be on disk and
performance. The use of "data=writeback" can cause
unwritten data to appear in files after an system crash or
power failure, which can be a security issue. However,
"data=ordered" mode can also result in major performance
problems, including seconds-long delays before an fsync()
call returns. For details, see:
http://ext4.wiki.kernel.org/index.php/Ext3_Data%3DOrdered_vs_Data%3DWriteback_mode
If you have been historically happy with ext3's performance,
data=ordered mode will be a safe choice and you should
answer "y" here. If you understand the reliability and data
privacy issues of data=writeback and are willing to make
that trade off, answer "n".
This is great. Ship it!
-VAL
I certainly agree - this is a vast improvement over what we have today,
thanks!
Ric
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