Date: Mon, 04 Sep 2000 15:38:34 -0400 From: Mike Tancsa <mike@sentex.net> To: Mike Smith <msmith@FreeBSD.ORG> Cc: "FreeBSDHW" <freebsd-hardware@FreeBSD.ORG> Subject: Re: Problems installing 4.1 on 3ware RAID 5200 & 6200 Message-ID: <4.2.2.20000904152548.03405b38@mail.sentex.net> In-Reply-To: <200009041934.MAA05065@mass.osd.bsdi.com> References: <Your message of "Mon, 04 Sep 2000 08:37:27 CDT." <005301c01675$4575b2e0$9e0e1b18@austin.rr.com>
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At 12:34 PM 9/4/2000 -0700, Mike Smith wrote:
> > I haven't tried RAID 0. The only other configuration I tried was installing
> > to a single drive (not in an array, but still connected to the 3Ware
> > controller). That worked just fine which is why I haven't shipped the card
> > back yet.Yes, doing newfs on a 30 GB partition takes upwards of an hour.
>
>The newfs issue tends to be misleading; it's not representative of the
>performance of the controller at all.
>
>If you newfs a redundant array that's background-initialising, it's slow.
>(Slower than it really should be, IMO.) However the real killer is that
>newfs uses the physio interface, and that runs into this issue from the
>twe(4) manpage:
>
>BUGS
>...
> The controller cannot handle I/O transfers that are not aligned to a
> 512-byte boundary. In order to support raw device access from user-
> space, the driver will perform alignment fixup on non-aligned
> data. This
> process is inefficient, and thus in order to obtain best performance us-
> er-space applications accessing the device should do so with aligned
> buffers.
>
>Newfs doesn't use aligned buffers...
Thanks for pointing this out. One thing that is not clear to me, how does
this explain the very poor performance in bonnie ? If the poor bonnie
results were being triggered by the alignment problem, would it not show
equally poor results in RAID0 mode as well ?
---Mike
--------------------------------------------------------------------
Mike Tancsa, tel +1 519 651 3400
Network Administration, mike@sentex.net
Sentex Communications www.sentex.net
Cambridge, Ontario Canada www.sentex.net/mike
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