Ext3 users - Feb 2003 - EXT3 and disk write back cache

Hi,

I have a few questions regarding EXT3 and disk write back cache:

1.	Will random power cycle cause data/metadata corruption on EXT3 running on
a hard disk with write back cache enabled?
2.	Will random power cycle cause EXT3 corruption when running on top of an
md RAID5 device with disk write back cache enabled?
3.	I understand Linux supports write barrier for IDE disks, does EXT3
utilize write barrier?  If so, will write barrier work for EXT3 running on
top of an md device?

Thanks,
Rob
------------------------------------------------------------
Boon Storage Technologies, Inc.
rgliu@sr5tech.com
(408)393-8998
http://www.sr5tech.com
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Hi,

On Thu, 2003-02-20 at 22:39, Robert Liu wrote:
> I have a few questions regarding EXT3 and disk write back cache:
> 
> 1.	Will random power cycle cause data/metadata corruption on EXT3 running
on
> a hard disk with write back cache enabled?
It might, unless the write-back caching still preserves the write
ordering.
> 2.	Will random power cycle cause EXT3 corruption when running on top of an
> md RAID5 device with disk write back cache enabled?
Software RAID5 will *increase* your sensitivity to writeback caching
effects, not reduce it.
> 3.	I understand Linux supports write barrier for IDE disks, does EXT3
> utilize write barrier?  If so, will write barrier work for EXT3 running on
> top of an md device?
There have been patches proposed for barriers, but none that work on an
md device, and they aren't in 2.4 at present.

Cheers,
 Stephen