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Re: mail queue's, ext3 data=journal and sync-mount

On Tue, 20 Aug 2002 11:54, Philipp Schmidt wrote:
> within this discussion, i got the idea to put an external journal for
> the ext3fs on an raid1-volume the real data on a raid5, hopefully, when
> writing the journal out to the disk having more data to be written an
> once - this would be worth a try but i don't have the hardware to try
> this and bad expirences with software raid5.

Ideally if using data journalling then the transactions would be large enough 
to encompass entire stripes and remove most of the RAID-5 penalty for small 

However having an external journal on a RAID-1 array that's used for nothing 
else would really help performance.  Also make sure that you are using the 
fastest part of the disks used for the RAID-1 (use ZCAV to measure it).  The 
start of the disks seems to always be the fastest for IDE disks, but 
apparently SCSI disks sometimes do things differently so a benchmark would be 
a good idea.

For best performance investigate some sort of battery-backed RAM disk device.

Another issue of RAID-5 is that when writing a stripe if the power fails it 
may write some blocks of the stripe but not all.  Having journalled data and 
an external journal on a non-RAID-5 should solve that.

I do not get viruses because I do not use MS software.
If you use Outlook then please do not put my email address in your
address-book so that WHEN you get a virus it won't use my address in the
>From field.

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