"Mark W. Krentel" wrote: > Dump still works on a mounted file system in Freebsd, right? That is, > a write that completes before dump is started will be in the dump, > even if the data is in memory? I don't mean writing to a file during > the dump, that's a separate problem. > > I only recently learned that this doesn't work in Linux and I wanted > to check that it's (still?) ok in Freebsd. Apparently, in the 2.4 > Linux kernels, the buffer and page caches make it impossible for dump > to always get the correct version of a file, even if there are no > writes during the dump. It takes a umount before dump will see all of > the changes (yuck). > > Anyone know about Solaris, IRIX, etc?
Dump on a live FS is always risky. FreeBSD in 4.x and earlier will have up to about a 30 second delay before a write() makes it to physical disk. However, 5.x have snapshots where you can take a virtual snapshot of the file system device as it existed at the instant that you create it. You can then take a coherent dump that *will* be accurate. fsck uses snapshots in 5.x to do background fsck to reclaim lost resources. 5.0 should be released sometime this century. :-) Cheers, -Peter -- Peter Wemm - [EMAIL PROTECTED]; [EMAIL PROTECTED]; [EMAIL PROTECTED] "All of this is for nothing if we don't go to the stars" - JMS/B5 To Unsubscribe: send mail to [EMAIL PROTECTED] with "unsubscribe freebsd-hackers" in the body of the message
