Date: Sun, 29 Jul 2001 20:32:03 +0000 (UTC) From: naddy@mips.inka.de (Christian Weisgerber) To: freebsd-hardware@freebsd.org Subject: Re: DLT 4000 throughput and cstream Message-ID: <9k1rs3$1chj$1@kemoauc.mips.inka.de> References: <3B62D0CF.27C12B9@we.lc.ehu.es>
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Jose M. Alcaide <jose@we.lc.ehu.es> wrote: > I am pipelining dump(8) to cstream (ports/misc/cstream), using this > command line: FWIW, when I tried cstream some time ago it didn't appear to live up to its author's claims. Personally I use misc/buffer for this purpose. > However, I am getting what a I think is a too low transfer rate > (compression is enabled on the DLT unit). This is what I get with > iostat(8): > > sa0 > KB/t tps MB/s > 60.59 22 1.31 I get 1.4 MB/s with compression _disabled_. > Is this the expected throughput for a DLT 4000? Well, does the tape stream? I.e. does it run continously, or does it drop back to stop-and-go mode? I can't get my DLT4000 to stream properly with compression enabled. I have no idea why. The disk delivers 8+ MB/s, disk and tape are on different SCSI buses. I dump(8) to a holding partition and transfer the complete archive from there to tape. I'm left with the conclusion that the DLT4000's compression engine can't keep up. -- Christian "naddy" Weisgerber naddy@mips.inka.de To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hardware" in the body of the message
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