Date: Mon, 27 Jul 1998 18:26:08 +0100 (BST) From: Philip Inglesant <philip@dircon.net> To: freebsd-stable@FreeBSD.ORG Subject: dump/restore and large filesystem problems Message-ID: <Pine.BSI.3.91.980727173721.20621A-100000@admin.dircon.net>
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This problem was reported by tom@uniserve.com in April, but i haven't seen any convincing answer to it, and it is still a problem for us. I have this exact problem with a large (16GB) file system. It is nothing to do with sparse files, back tapes, networks, or anything else like that. I can dump and pipe it into a restore, and the "hole in dump" happens right away. I did some hacking in the source, and it seems that the "maps" dumped at the start of the tape can exceed TP_NINDIR (which is half a basic tape block, or 512) blocks. The significance of this is that the c_addr table, which has a non-zero value for each block in the ext part of the dump, fits in 512 bytes (look in /usr/include/protocols/dumprestore.h), and the whole header fits in a basic 1kb block. For debugging, I got restore to fprintf the value of c_count, which is the size of the next part of the dump, for which the c_addr table has to have a value for each block. On the type TS_CLRI map (that's map of inodes deleted), on this particular 16Gb file system, it showed a value of 1019. Obviously, on other file systems it would be some other value, but there's no reason at all to assume it will always be < 512. I have a hacked version of dump that puts the two initial maps (cleared inodes and the file dump list) onto tape in much the same way as the actual files - a header guaranteed to be < 1 basic tape block, followed by 512 or fewer blocks of dump, followed by another header and so on as necessary, and a hacked version of restore to read dumps done this way. It seems to work but i haven't really tested it well. Maybe someone with more knowledge of BSD dump/restore would like to comment. Philip Inglesant Direct Connection To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-stable" in the body of the message
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