Date: Tue, 16 Jul 2002 00:54:12 -0400 From: Brian T.Schellenberger <bts@babbleon.org> To: "Tortise@Paradise" <tortise@paradise.net.nz>, "Nick Sayer" <nsayer@quack.kfu.com> Cc: <freebsd-stable@FreeBSD.ORG> Subject: Re: Poor Mans Software raid 1 on root partition? Message-ID: <20020716045412.71168BB2C@this_is.fake.com> In-Reply-To: <00a601c22c79$1671d8e0$0900a8c0@P1200n> References: <25f401c228d4$a3482fb0$1a01000a@area51> <3D338329.4010205@quack.kfu.com> <00a601c22c79$1671d8e0$0900a8c0@P1200n>
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On Monday 15 July 2002 11:30 pm, tortise@paradise.net.nz wrote: | 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? I don't think that you said anything about dd in the first place. FWIW, I mirror with "rsync." Even though it's not really remote it works nice for informal mirroring. | | > 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 -- Brian, the man from Babble-On . . . . bts@babbleon.org (personal) http://www.babbleon.org http://www.eff.org http://www.programming-freedom.org To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-stable" in the body of the message
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