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From: alan@shodha.enet.dec.com ( Alan's Home for Wayward Notes File.)
Newsgroups: comp.sys.dec
Subject: Re: 5820 performance ( IO )
Summary: How fast is too slow?
Message-ID: <1909@shodha.enet.dec.com>
Date: 31 Oct 90 15:49:24 GMT
References: <1990Oct29.151224.21573@mlb.semi.harris.com>
Organization: Digital Equipment Corp. - Colorado Springs, CO.
Lines: 48

In article <1990Oct29.151224.21573@mlb.semi.harris.com>, jdr@jrx.mlb.semi.harris.com (Jim Ray) writes:
> Has anyone had experience with 5820's connected to HSC70's ( with
> RA92's )?

	Nope.  But is a VAX 8800 with an HSC70 and RA90s close
	enough.  I'd expect them to be similiar.
> 
> I have been less than impressed so far with the IO performance and would
> like to find out if anyone else has had similar experiences with the 5820.
> 
> What range of IO performance do you get ?

	Sequential reading of large files is around 800 KB/sec.  The
	block size of the file system is 8KB and the rotdelay is 4.
	Writes are about 500 KB/sec.
> 
> Also, we have the CI configured as another network and have been transmitting
> data to the other 5820's via this mechanism.  It appears to be 2x slower than
> going over the ethernet connection.

	I would expect the CI be faster than the Ethernet, but the
	other system on my CI is a VAX 8300 and isn't fast enough
	be interesting.
> 
> I would like to find out if we are doing something wrong or if this
> is normal performance with the 5820.  Interresting that the DS5000 IO
> performance even with scsi drives appears to be faster than the 5820.

	I've never had my hands on a 58xx to find out what "normal".
	I would expect it to be comparable with similiarly configued
	VAX 8800 or VAX 6000-4xx/5xx.  A reasonable SCSI disk with a 
	read-ahead cache is nearly always going to be faster than an 
	SDI disk.
> 
> Again, since we just installed these machines ( about a month ago ), it could
> be related to setup.

	If you have spare partition, play around with tunefs(8), rotdelay
	and maxcontig.
> 
> --
> Jim Ray                                Harris Semiconductor
> Internet:  jdr@mlb.semi.harris.com     PO Box 883   MS 62B-022
> Phone:     (407) 729-5059              Melbourne, FL  32901


-- 
Alan Rollow				alan@nabeth.enet.dec.com