[dundee] ELF yourself encryption

Andy Smith andy at strugglers.net
Tue Jun 23 05:18:36 UTC 2009


Hi Lee,

On Fri, Jun 19, 2009 at 04:16:42PM +0000, Lee Hughes wrote:
> a raid controller is just more stuff to go wrong in my opinion,  when 
> servers were single core affairs, the offloading raid function to a piece
> of hardware made sense. The less hardware you have in a box the better,
> perfect design is not when you can add stuff, it's when you can't take
> anything more away.

Something I have found is that under moderate write load, the verify
cron job that comes with mdadm can take days to complete and
performance is impacted whilst doing so.

On the other hand, a "verify" task on my 3ware controllers with the
same disks and RAID-10 layout completes in around 12 hours on the
slowest setting and is not noticeable.

I suspect that this is because with software RAID all the data from
the disks must go across the PCIe bus and through the kernel to be
checked, whereas the 3ware card itself does the verify involving
only the disks and bus.

So, I'm having to use fairly cheap hardware RAID (3ware) on most of
my servers, but am still happy with Linux md RAID for home machines.

Cheers,
Andy

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