From owner-freebsd-hackers Fri Nov 13 15:28:15 1998 Return-Path: Received: (from majordom@localhost) by hub.freebsd.org (8.8.8/8.8.8) id PAA19803 for freebsd-hackers-outgoing; Fri, 13 Nov 1998 15:28:15 -0800 (PST) (envelope-from owner-freebsd-hackers@FreeBSD.ORG) Received: from apollo.backplane.com (apollo.backplane.com [209.157.86.2]) by hub.freebsd.org (8.8.8/8.8.8) with ESMTP id PAA19797 for ; Fri, 13 Nov 1998 15:28:12 -0800 (PST) (envelope-from dillon@apollo.backplane.com) Received: (from dillon@localhost) by apollo.backplane.com (8.9.1/8.9.1) id PAA06232; Fri, 13 Nov 1998 15:27:47 -0800 (PST) (envelope-from dillon) Date: Fri, 13 Nov 1998 15:27:47 -0800 (PST) From: Matthew Dillon Message-Id: <199811132327.PAA06232@apollo.backplane.com> To: dag-erli@ifi.uio.no (Dag-Erling C. =?iso-8859-1?Q?Sm=F8rgrav?= ) Cc: Marc Slemko , David Wolfskill , hackers@FreeBSD.ORG Subject: Re: dump(8) very slow References: <199811131747.JAA05198@apollo.backplane.com> Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG :Matthew Dillon writes: :> I gzip -2 the dump output on :> the remote machine before it comes back through the ssh pipe. : :Why not turn on compression in ssh (-C) rather than add an extra stage :to the pipeline? I am saving gzip'd dumps to tape directly. I know, I know, it means you'd better not have a tape error in a dump. Too bad. Exabytes do duel-head verification anyway, though you definitely have to clean the drives twice a week (at the volume levels we push through the drives) to maintain optimal performance (which is 3 MBytes/sec for an exabyte Mammoth). The backup machine is already cpu-limited doing the encryption (even though the network is switched and secured, we don't trust it). If I had the backup machine do compression (ssh -C) as well, or if I had it gunzip the remotely-gzip'd dump, the 2.5 MBytes/sec would because 1.5 MBytes/sec. If I have the tape drive do the compression, I get sub-optimal capacity verses pushing gzip'd dumps to a tape drive in uncompressed mode. Sometimes I think about turning off ssh's link encryption, but then I think a little more and say 'nahh, better to leave it on'. Once we upgrade the machine we'll be able to dump 6 MBytes/sec over the network, which matches two 3 MByte/sec tape drives very well. -Matt :DES :-- :Dag-Erling Smørgrav - dag-erli@ifi.uio.no : :To Unsubscribe: send mail to majordomo@FreeBSD.org :with "unsubscribe freebsd-hackers" in the body of the message : Matthew Dillon Engineering, HiWay Technologies, Inc. & BEST Internet Communications & God knows what else. (Please include original email in any response) To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message