Nice looking 'disk array'

[ted leslie]

Good timing for me for this thread,

i have just finished setting up 4 or so servers with 3ware PCI-X 8 and
12 channel sata raid controllers.

I was thinking of setting up another involving about 16 drives,
and perhaps a read throughput (not buffered) of about 1GB / second,
the most i have got with a 8channel (8 drives) is about 500-600 MB/sec,
so I am hoping a 16 channel (16 drive) could push me over 1GB/sec
transfer.

now if i take the linux software approach , I'd have to get
about 12 sata channels as a pci-x expansion card (+4 on board).
I get the 3ware 16 channel for about 1000$

i wonder how the linux software raid with PCI-X straight sata expansion
cards is going to compare with cost and performance to a 
3ware 16 channel in a single PCI-X slot?

also , having a UPS on a system doing software raid, isnt the equivalent
of a battery backup on a 3ware card,
you could have a failure between UPS and CPU, or a kernel panic
(granted a KP is pretty rare these days).

If I can get 1GB/s transfer from a linux software raid sol'n , 
and its faster and cheaper then the 3ware .... man I am going to
consider it!!
anyone tried?

I am going to hazard a guess that for a array rebuild, the HW raid has
got to be preferable? but hopefully one isn't rebuilding to often.

-tl


On Mon, 2007-01-29 at 18:09 -0500, Lennart Sorensen wrote:
> On Mon, Jan 29, 2007 at 05:10:08PM -0500, Dave Cramer wrote:
> > So what happens in software raid when someone pulls the plug on the  
> > machine ???
> 
> Anything still in system ram is lost.
> 
> > and if you want fast cheap hardware RAID controllers check out Areca.  
> > 1GB optional battery backed up write cache means the answer to the  
> > above question is nothing bad.
> 
> Anything still in system ram is lost.
> 
> Difference is that you get the ability to do some write caching in
> hardware, which you don't get above.  Until the OS decides it is time to
> write though, both solutions are equal.  The battery backed hardware
> raid can finish the I/O sooner for the OS though, and not loose it.  So
> small benefit there.  Surprisingly many hardware raid cards don't have
> battery backed caches though.
> 
> Besides I have a UPS.
> 
> --
> Len Sorensen
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