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From: mika ruohotie <bsdscsi@shadows.aeon.net>
Message-Id: <199609270938.MAA20281@shadows.aeon.net>
Subject: Re: striping/mirroring?
To: asami@FreeBSD.ORG (Satoshi Asami)
Date: Fri, 27 Sep 1996 12:38:32 +0300 (EET DST)
Cc: freebsd-scsi@FreeBSD.ORG
In-Reply-To: <199609270236.TAA18470@silvia.HIP.Berkeley.EDU> from Satoshi Asami at "Sep 26, 96 07:36:32 pm"
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>  * now, what i want to know is which scsi drives would give me the best
>  * performance/reliability... i've personally thought using barracuda 4lp,
>  * but i feel a bit sceptic it's reliability...
> What performance?  Sequential or random?  I'm assuming that ga586hx512

performance as getting as high as possible read/write speed to/from
hard drives.

> is an Intel 430 HX with 512KB of cache, that's as good as it gets as
> far as motherboards go.

yes, it's gigabyte's board that's tested being the 2nd fastest board
on market, only tyan is faster... (http://www.u-net.com/sysdoc) and has
the said chipset, and cache.

> If you want to maximize sequential access, you'll need about 6 or 7
> disks to stripe across them, you'll get to about 28 MB/s with the
> option "I586_FAST_BCOPY".  For random access, you'll need more like 30 
> drives through the filesystem to max out the motherboard.

ok

only 28 mb/s? isnt it possible to get more speed?

>  * would mirror it to one... can i? how, if i can?
> That isn't mirroring. ;)

but what?

> If you have 2N drives, mirroring will make that look like a N-disk
> ccd.

???

i meant, that: while striping using 4 or something drives, i would love
to be able to mirror whatever i am striping to one disk. just to be
safe...

and now that i think of it... is it even possible? anyone?

i would not mind if that safe copy would not run as fast as the rest of
the filesystem, but that i would have atleast some recent version of the
system somewhere on _one_ disk...

and while thinking more... is it sane? =)

> Satoshi


mickey
--
     mika@aeon.net    mika ruohotie