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From: pja@ralph.lafayette.la.us (Pete Alleman)
Newsgroups: comp.periphs.scsi
Subject: Re: SLOW WRITE ON OPTICAL ERASABLES
Keywords: OPTICAL, PERFORMANCE
Message-ID: <1991Jun21.182311.21416@ralph.lafayette.la.us>
Date: 21 Jun 91 18:23:11 GMT
References: <1080@camco.Celestial.COM> <910@cadlab.sublink.ORG>
Organization: Consulting
Lines: 19

>bill@camco.Celestial.COM (Bill Campbell) writes:
>	ctar -Cvf /mnt/tarfile /bin	# 0.5MB/Min, optical
>Is this typical of erasable write speeds?  I expected them to be

We use HP magneto-optical drives for logging real-time data.
The standard write runs about 300KB/sec with large block sizes
(400KB or so).  My application must sustain 350KB/sec, so
we have to pre-erase the disks and tell the drive not to
erase before each write.  The drive can sustain somewhere around
600KB/sec in this mode.

These drives have two limitations that can make them very slow.
They turn at 2400 rpm  and require two revelutions for each write,
and they have a VERY slow seek.  Try running tar to the raw device
with blocking set to 400KB.

-- 
Pete Alleman
	pja@ralph.lafayette.la.us