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Vasu, > hi all, > I have two physical harddisks /dev/hda1 and /hdb You have two physical hard disks /dev/hda and /dev/hdb. - hda contains a partition /dev/hda1 you want to backup. - hdb contains at least one partition /dev/hdb1 on which you want to put the backup (unless you use the raw HD formatted). I'll assume you'll backup to a file in /dev/hdb1. > 1) i want to copy drive (take backup) to a file ( in /hdb)using dd. > So how much space( in terms percentage)more is required in /hdb > for it to be copied successfully. Don't know the right answer. That shall not need too much overhead. But I would point out that /dev/hda1 can _not_ be a live filesystem (I mean you can't do that if /dev/hda1 is mounted, for example as your root FS), if it is, you'll end up with a backup containing errors (due to cache). $ umount /dev/hda1 $ mount /dev/hdb1 /hdb $ dd if=/dev/hda1 of=/hdb/backup But if you want, you can also do this: $ umount /dev/hda1 /dev/hdb1 $ dd if=/dev/hda1 of=/dev/hdb1 That way, /dev/hdb1 needs to be exactly the size of /dev/hda1 > 2) After copying using dd if=/dev/hda1 of=/hdb/backup > how to retrive it back again in terms of directories and > sub-directories and files. Two solutions here: - you want to restore /dev/hda1 at the state it was at backup, then you dd if=/hdb/backup of=/dev/hda1 (Note that once again /dev/hda1 must _not_ be mounted) - or you just want to access the backup. In this case you need a loop device: mount -o loop /hdb/backup /mnt/backup You'll need loop support in your kernel (either built-in or module). That way, you can compare the FS against the backup, and/or restore part of it (by cp'ing files/directories). Correct me where I'm wrong. Regards, Yann E. MORIN. -- .---------------------------.----------------------.------------------. | Yann E. MORIN | Real-Time Embedded | ASCII RIBBON /"\ | | phone (+33/0) 299 055 231 | Software Designer | CAMPAIGN \ / | | fax (+33/0) 299 055 221 °----------------------: AGAINST X | | yann.morin@atosorigin.com www.atosorigin.com | HTML MAIL / \ | °--------------------------------------------------°------------------° - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ | ||||||||||||
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