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From: Linda Walsh <xfs@tlinx.org>
To: xfs-oss <xfs@oss.sgi.com>
Subject: get filename->inode mappings in bulk for a live fs?
Date: Thu, 04 Oct 2012 08:30:20 -0700	[thread overview]
Message-ID: <506DAB8C.9000601@tlinx.org> (raw)

I notice that attempts to use utils to get name->inode mappings
(xfs_ncheck) seem to have no option to operate on a mounted filesystem.

Is it practical to xfs_freeze such a file system and then ncheck it? or would
freezing it simply freeze the fact that it is open and provide no benefit?

So how can I get an inode->block mapping on a live fs.

I'm not worried about some smallish number of cases that might be inaccurate.

Out of ~5M files on my most populous volume, having even 1000 files w/wrong
info would be less than .02% -- which would be bad if I wanted an exact backup,
but for purposes a quick-fuzzy look at files that have changed and are finished
being changed (vs. the ones being changed right now),

The man page for xfs_freeze mentions using it to make snapshots -- how long
does such a snapshot usually take?  I.e. how long would a file system be frozen?
Is it something that would take a few ms, few seconds, or multiple minutes?

This may be a weird idea, but I seem to remember when lvm takes a snapshot
it moves the live volume aside and begins to use COW segments to hold changes.

Is it possible to xfs-freeze a COW copy so access to the original FS isn't
suspended thus making the time period of an xfs_freeze/dump_names less
critical?

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             reply	other threads:[~2012-10-04 15:28 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-10-04 15:30 Linda Walsh [this message]
2012-10-04 18:01 ` get filename->inode mappings in bulk for a live fs? Greg Freemyer
2012-10-04 18:29   ` Linda Walsh
2012-10-04 18:59     ` Greg Freemyer
2012-10-04 22:39   ` xfs_freeze same as umount? How is that helpful? Linda Walsh
2012-10-04 23:32     ` Dave Chinner
2012-10-05  0:10       ` Linda Walsh
2012-10-05  0:36         ` Dave Chinner
2012-10-04 22:49 ` get filename->inode mappings in bulk for a live fs? Dave Chinner

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