Michael Tokarev said: (by the date of Tue, 09 Oct 2007 02:52:06 +0400) > Janek Kozicki wrote: > > Hello, > > > > Recently I started to use mdadm and I'm very impressed by its > > capabilities. > > > > I have raid0 (250+250 GB) on my workstation. And I want to have > > raid5 (4*500 = 1500 GB) on my backup machine. > > Hmm. Are you sure you need that much space on the backup, to > start with? Maybe better backup strategy will help to avoid > hardware costs? Such as using rsync for backups as discussed > on this mailinglist about a month back (rsync is able to keep > many ready to use copies of your filesystems but only store > files that actually changed since the last backup, thus > requiring much less space than many full backups). yes, exactly. I am using rsnapshot, which is based on rsync and hardlinks. It works exceptionally well - to my knowledge it's the best backup solution I have ever seen. With plugin scripts I am even mounting an lvm-snapshot of the drive being backupped. from command 'rsnapshot du' I can see how many space is used (but each directory tree is a full backup (made with hardlinks)): 278G /backup/.sync 454M /backup/hourly.0/ 515M /backup/hourly.1/ 527M /backup/daily.0/ 30G /backup/daily.1/ 21G /backup/daily.2/ 561M /backup/daily.3/ 1.6G /backup/daily.4/ 3.0G /backup/daily.5/ 594M /backup/daily.6/ 1.4G /backup/weekly.0/ 11G /backup/weekly.1/ 9.3G /backup/weekly.2/ 23G /backup/weekly.3/ 33G /backup/monthly.0/ 3.7G /backup/monthly.1/ 415G total > It's definitely not possible with raid5. Only option is to create a > raid5 array consisting of less drives than it should contain at the > end, and reshape it when you get more drives, as others noted in this > thread. But do note the following points: <..snip..> yes, I am aware of all those problems you listed. The data I'm talking about is already a backup. While the real data is on my workstation (a different linux box - albeit only the newest version of my data). Only losing both of them simultaneoulsy will be catastrophic for me. So I am inclined to do some experiments with the backup drives configuration, while still doing my best at not losing it. An exercise, you know :) > > is it just a pipe dream? > > I'd say it is... ;) oh well. But I learnt a lot from your answers, thanks a lot! PS: I'm receiving some mailing list posts twice, anybody knows why? I'm used to mailman but looks like majordomo is being configured in a different way - I cannot find a configure page. (I just subscribed). -- Janek Kozicki | - To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
