Re: Backups: rsync, software RAID, other strategies?

From: Bob Johnson (bob89_at_bobj.org)
Date: 03/12/04

  • Next message: Kirk Strauser: "Re: how does linux emulation work?"
    To: Dany Nativel <dany_list@natzo.com>
    Date: Fri, 12 Mar 2004 00:14:51 -0500
    
    

    Thanks for pointing me to these tools. I may not use Unison on this
    particular project, but I think it will be the next project after the
    backup server is finalized!

    - Bob

    On Monday 08 March 2004 02:22 am, Dany Nativel <Dany Nativel
    <dany_list@natzo.com>> wrote:
    > Hi Bob,
    >
    > I use the following configuration on my file server.
    > It's a small cube based on a low power mini-ITX EPIA 5000 motherboard
    > (fanless) and running two 120GB HDDs.
    > I looked at RAID but it doesn't help solving one of the potential
    > issue ... me, user removing files that are not supposed to be removed
    > so incremental backup is a plus. This baby is powered by FreeBSD
    > 5.2.1 (used to be Debian).
    >
    > DISK 0 (live)
    > 128M ad0s1a /
    > 512M ad0s1b swap
    > 128M ad0s1d /var
    > 200M ad0s1e /tmp
    > 3200MB ad0s1f /usr
    > 110GB ad0s2d /data
    >
    > DISK 1 (Backup)
    > ad2s1d 128M /backup/os/root
    > ad2s0b 512M swap
    > ad2s1e 128M /backup/os/var
    > ad2s1f 200M /backup/os/tmp
    > ad2s1g 3199M /backup/os/usr
    > ad2s2d 108G /backup/data/backup
    >
    >
    > I use 3 different programs :
    > - Unison (http://www.cis.upenn.edu/~bcpierce/unison/): 2-way
    > synchronization using rsync/ssh, multi-platform graphical interface.
    > I can have the same files on my file server, laptop running win2k as
    > well as my desktop running BSD. Very convenient especially with
    > laptops when you can't be connected all the time.Very fast too (only
    > transmit diffs) - rsync (man rsync) : typical rsync that will mirror
    > the source to the destination
    > - rdiff-backup (http://rdiff-backup.stanford.edu/index.html): it's
    > based on rsync but you get the advantage of incremental backups so
    > you can restore from a specific date. You can also purge the backup
    > by removing old stuff. No fancy file format, just .gz for the
    > diffs.
    >
    > Here is how I use those tools :
    > /data/current/user0_live (DISK 0) <----> UNISON : 2-way
    > synchronization with laptop/desktop
    > /data/current/user0_incremental (DISK 0) <----> RDIFF-BACKUP :
    > incremental backup of user0_live using RDIFF system
    > /backup/data/backup/user0_incremental (DISK1) <----> RSYNC : quick
    > mirror of the already incremental backup
    >
    > /backup/data/backup/pictures (DISK1) <----> RDIFF-BACKUP
    > : in this case, rdiff-backup between drive0 and drive1 (no
    > incremental on disk0)
    >
    > /backup/os/root (DISK1) <----> DUMP : 1:1 copy of the live root
    > fs /backup/os/tmp (DISK1)
    > /backup/os/var (DISK1)
    >
    > /backup/os/usr (DISK1) <----> RSYNC : (with -delete option)
    > for a quick mirror of current /usr
    >
    > PS: for user0, there are two copies of the data on disk0, 1 live
    > synchronized with Unison and another one which is an incremental of
    > the first one. For less critical data (like /data/current/pictures)
    > I use rdiff-backup between disk0 and disk1. In that case I would lose
    > incremental backups if disk1 fails.
    >
    > I've simulated a crisis situation by removing the drive0 and swapping
    > it with drive1. It worked (except for those entries in fstab
    > referring to disk1).
    >
    > I have a cron job taking of the different backups at night.
    >
    > #!/bin/sh
    >
    > # Duplicate /
    > # erase slive before mirroring, any other way?
    > umount /backup/os/root
    > newfs /dev/ad2s1a
    > mount /backup/os/root
    > # dump with 'live filesystem' option
    > dump -0 -L -f - /dev/ad0s1a | (cd /backup/os/root ; restore -r -v -f
    > -)
    >
    > # Duplicate /var
    > umount /backup/os/var
    > newfs /dev/ad2s1d
    > mount /backup/os/var
    > dump -0 -L -f - /dev/ad0s1d | (cd /backup/os/var ; restore -r -v -f
    > -)
    >
    > # Duplicate /tmp (probably a wate of time)
    > umount /backup/os/tmp
    > newfs /dev/ad2s1e
    > mount /backup/os/tmp
    > dump -0 -L -f - /dev/ad0s1e | (cd /backup/os/tmp ; restore -r -v -f
    > -)
    >
    > # incremental backup of the ./pictures directory on the second drive
    > rdiff-backup /data/current/pictures /backup/data/backup/pictures
    >
    > # First, incremental of the user0_live dir on the same drive then
    > rsync on the second drive
    > rdiff-backup /data/current/user0_live /data/current/user0_incremental
    > rsync -a --delete /data/current/user0_incremental/
    > /backup/data/backup/user0_incremental
    >
    >
    > The only I don't like is the NEWFS command. Is there a cleaner way to
    > do this dump ?
    >
    > I use this configuration is a non-critical installation (my house)
    > but it has been serving its purpose so far.
    > Dany
    >
    >
    > PS: On the rdiff-backup webpage there is a link to another tool call
    > duplicity (http://rdiff-backup.stanford.edu/duplicity.html). You can
    > do remote backup but in that case the image can be stored on a remote
    > FTP server and encrypted with GPG... sweet if you're planning to use
    > your ISP's disk space for backups!
    >
    > Bob Johnson wrote:
    > >A bunch of related questions:
    > >
    > >I'm setting up a small mail and file server. The mail server part
    > > will be Courier, while the file server part will primarily be used
    > > via NFS and Samba to store backups of my desktop and laptop
    > > computers.
    > >
    > >The system has a pair of WD1600JB 160 GB ATA 100 drives in it, both
    > > on a single Promise PDC20268 UDMA100 controller, but each on a
    > > separate channel (i.e. both are masters with no slaves). My plan
    > > is to use one of the drives as a backup for the other. I want to
    > > use a backup method that creates a mirror of the working drive so
    > > that if it fails, I can simply mount the backup in place of the
    > > working drive, and get back in business. The operating system will
    > > (probably) not be on either of these drives, they will only host
    > > /home where mail and backup files will reside.
    > >
    > >I've tentatively decided to synchronize the mirror to the working
    > > drive with rsync run once a night (perhaps more often later). This
    > > risks losing up to a day of mail, but that's probably not the end
    > > of the world. The reasoning I used was that if I use software
    > > RAID, an unexpected power failure during a large write operation
    > > (yes, it will be on a UPS) could corrupt both drives. Running
    > > rsync once a night would reduce the risk of a failure that damaged
    > > both drives, since their write activity would not be so strongly
    > > correlated.
    > >
    > >Is my fear of losing both drives in a software RAID (mirrored
    > > drives) configuration a reasonable one? Or is that not going to
    > > happen?
    > >
    > >If I use rsync with -delete to maintain a mirror of the primary
    > > drive, what happens when the primary drive fails? Is there a
    > > scenario that causes rsync to duplicate all the missing data on the
    > > primary drive by deleting it from the mirror drive (I've heard of
    > > this happening to someone, but I believe he was using a homegrown
    > > perl script rather than rsync).
    > >
    > >Is Courier compatible with this scheme? Or does it care about inode
    > >numbers or some such thing that will make the backup copy useless?
    > >
    > >Is there any chance it would make sense to use the Coda file system
    > > for this?
    > >
    > >Do any of the answers change if the mail server ends up on a remote
    > >system, but I still want the maildirs backed up on the file server?
    > >
    > >Any other suggestions that don't involve buying new hardware? An
    > > IDE RAID controller would be nice, but buying one isn't on my list
    > > of things to do. But if I DID break down and buy a new controller
    > > card, what should it be?
    > >
    > >Thanks,
    > >
    > >- Bob
    > >_______________________________________________
    > >freebsd-questions@freebsd.org mailing list
    > >http://lists.freebsd.org/mailman/listinfo/freebsd-questions
    > >To unsubscribe, send any mail to
    > > "freebsd-questions-unsubscribe@freebsd.org"
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  • Next message: Kirk Strauser: "Re: how does linux emulation work?"

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