Linked by Eugenia Loli on Sat 8th Jul 2006 04:54 UTC
General Unix Copying a live file system can be risky, especially if there are open files. You should also be careful to ensure that you don't accidentally overwrite a partition, or existing files, with the files you are trying to copy. With some careful thought, you can effectively migrate files reliably to take advantage of more space, even on a live system.
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RE: More Comfortable Way
by butters on Sat 8th Jul 2006 06:30 UTC in reply to "More Comfortable Way"
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Yes, you do need to edit the fstab, which is just one of the reasons why this is a disappointing article. He mentions editing the fstab at the very end, but he doesn't explain it in detail. Everything else in the article was explained like you explained how to edit the fstab (in too much detail for even an inexperienced UNIX sysadmin).

More importantly, he mades a really big deal of why migrating live filesystems is critical and how you need to be really clever in order to make sure the files are available throughout the process... and then he suprises me by suggesting a really simple process (the naive approach, in fact) that doesn't maintain filesystem availability. No matter whether you're migrating directories or filesystems using this process, the filesystem will be unavailable between the time when the source directory is renamed and when the new filesystem is mounted, or between the time when the source filesystem is unmounted and when the new filesystem is mounted. There's no simple way to make either transition atomic.

Another sore point is that he mades no mention of logical volume systems, which have dominated the UNIX space for many years. These systems have features for dynamically resizing volumes, and some (including Sun's ZFS and IBM's JFS2) support _real_ live volume migration across storage devices.

If I wanted to learn how to use cp, tar, and my shell, I would read their man pages. That's what this article is. If you haven't read it yet, don't bother wasting your time... This guy just isn't very knowledgable in this subject.

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