Date: Tue, 16 Jul 2002 15:30:09 +1200 From: "Tortise@Paradise" <tortise@paradise.net.nz> To: "Nick Sayer" <nsayer@quack.kfu.com> Cc: <freebsd-stable@freebsd.org> Subject: Re: Poor Mans Software raid 1 on root partition? Message-ID: <00a601c22c79$1671d8e0$0900a8c0@P1200n> References: <25f401c228d4$a3482fb0$1a01000a@area51><20020711091015.B51520@flake.decibel.org><20020711200902.3653b534.steve@sohara.org><20020713032546.GD61459@wantadilla.lemis.com><20020713075109.06ecf02f.steve@sohara.org><20020713100218.B284@twincat.vladsempire.net><20020713222745.00281f72.steve@sohara.org><20020714004247.GB16279@wantadilla.lemis.com> <20020714071524.1587f419.steve@sohara.org> <007801c22c6c$9dc32fe0$0900a8c0@P1200n> <3D338329.4010205@quack.kfu.com>
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Nick Many thanks for your detailed and considered response. May I interact with it? I shall presume I may. > If you don't want a tape drive, it's still a better idea to do dumps to > another disk rather than dd. Why? > > 1. You can compress the output of dump. I prefer to have a (potentially) running bootable backup drive, so it can be "hot swapped." (Well almost) > 2. You don't have to have identically partitioned disks Would I have to, to do that???? > > 3. You won't get a "clean" filesystem copying it with dd. In fact, the > source filesystem may change enough over the course of the dd that the > resulting image may be completely useless. mmm Now that is a problem to overcome. Maybe I need Dump and restore to the backup HDD? > 4. You can potentially store many, many days worth of backups on the > alternate drive. This lets you restore not just last night's backup, but > potentially last *week's*. And presumably I could do this on multiple HDD's also? I am afraid I am biased by HDD copying. In my experience it works. Almost always. Can the same be said for Tape drives? And there is no need to frig around restoring so up running more quickly. Copying between HDD's is generally quicker than tapes. (Well it was once) > Yes, doing a restore takes a little more time than simply booting the > other drive. But in practice, the likelyhood that you will really *need* > to do so is sufficiently low as to not be worthwhile, IMHO. I guess that depends on how old your HDD is. The one in mind is old. (1G is old isn't it??) However in my (limited) experience I have had more new high performance drives fail under warranty than old ones..... The 1G must be due to expire....LOL Its mate did yrs ago..... > The only reason to consider software raid for a truly mission critical > application is if you've got a really large dataset in an external box > that you can move from one machine to another if you need to get back up > quickly. In that circumstance, presumably the contents of the system > disk of the machine don't matter, meaning that the application would > come back on line simply by moving the disk to another machine and > restarting it. This is what I want, that is an acceptable scenario for me, especially in terms of time input to fix and the (high) likelihood of it working..... If that's unreasonable, then the whole machine requires > RAID (among other things), which means you'll be getting a hardware RAID. IDE hardware RAID remains an option, (I think the promise cards are supported, this is not 100% clear) but given I have some spare SCSI HDD floating surplus I'd rather use them for now..... > But don't ever forget that RAID won't help you if you accidently do an > rm -rf / as root. :-) Data integrity is NOT a substitute for good backups. Point well made. There is no backup panacea..... We have to do what we judge to be acceptable....and cost effective and what we can live with in the event of...... Any further comments welcomed, especially anything pointing me in a direction to proceed with. Regards David Hingston MB ChB MBA _________________________________________________________________________ tortoise@paradise.net.nz http://hingston.yi.org/ http://pcmc.yi.org/ If you seek a digitally signed response please advise. If you received a warning on reading this e-mail, please go to http://www.baycorpid.com/settings/email.asp?CA=healthcert to update your settings ----- Original Message ----- From: "Nick Sayer" <nsayer@quack.kfu.com> To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-stable" in the body of the message
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