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c618f87cd2
Deduplicated send and receive is deprecated. To ease migration to the new dedup-send-less world, the commit adds a `zstream redup` utility to convert deduplicated send streams to normal streams, so that they can continue to be received indefinitely. The new `zstream` command also replaces the functionality of `zstreamdump`, by way of the `zstream dump` subcommand. The `zstreamdump` command is replaced by a shell script which invokes `zstream dump`. The way that `zstream redup` works under the hood is that as we read the send stream, we build up a hash table which maps from `<GUID, object, offset> -> <file_offset>`. Whenever we see a WRITE record, we add a new entry to the hash table, which indicates where in the stream file to find the WRITE record for this block. (The key is `drr_toguid, drr_object, drr_offset`.) For entries other than WRITE_BYREF, we pass them through unchanged (except for the running checksum, which is recalculated). For WRITE_BYREF records, we change them to WRITE records. We find the referenced WRITE record by looking in the hash table (for the record with key `drr_refguid, drr_refobject, drr_refoffset`), and then reading the record header and payload from the specified offset in the stream file. This is why the stream can not be a pipe. The found WRITE record replaces the WRITE_BYREF record, with its `drr_toguid`, `drr_object`, and `drr_offset` fields changed to be the same as the WRITE_BYREF's (i.e. we are writing the same logical block, but with the data supplied by the previous WRITE record). This algorithm requires memory proportional to the number of WRITE records (same as `zfs send -D`), but the size per WRITE record is relatively low (40 bytes, vs. 72 for `zfs send -D`). A 1TB send stream with 8KB blocks (`recordsize=8k`) would use around 5GB of RAM to "redup". Reviewed-by: Jorgen Lundman <lundman@lundman.net> Reviewed-by: Paul Dagnelie <pcd@delphix.com> Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov> Signed-off-by: Matthew Ahrens <mahrens@delphix.com> Closes #10124 Closes #10156
62 lines
1.3 KiB
C
62 lines
1.3 KiB
C
/*
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* CDDL HEADER START
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*
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* This file and its contents are supplied under the terms of the
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* Common Development and Distribution License ("CDDL"), version 1.0.
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* You may only use this file in accordance with the terms of version
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* 1.0 of the CDDL.
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*
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* A full copy of the text of the CDDL should have accompanied this
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* source. A copy of the CDDL is also available via the Internet at
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* http://www.illumos.org/license/CDDL.
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*
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* CDDL HEADER END
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*/
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/*
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* Copyright (c) 2020 by Delphix. All rights reserved.
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*/
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <fcntl.h>
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#include <ctype.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <strings.h>
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#include <unistd.h>
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#include <libintl.h>
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#include <stddef.h>
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#include <libzfs.h>
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#include "zstream.h"
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void
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zstream_usage(void)
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{
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(void) fprintf(stderr,
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"usage: zstream command args ...\n"
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"Available commands are:\n"
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"\n"
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"\tzstream dump [-vCd] FILE\n"
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"\t... | zstream dump [-vCd]\n"
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"\n"
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"\tzstream redup [-v] FILE | ...\n");
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exit(1);
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}
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int
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main(int argc, char *argv[])
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{
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if (argc < 2)
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zstream_usage();
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char *subcommand = argv[1];
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if (strcmp(subcommand, "dump") == 0) {
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return (zstream_do_dump(argc - 1, argv + 1));
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} else if (strcmp(subcommand, "redup") == 0) {
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return (zstream_do_redup(argc - 1, argv + 1));
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} else {
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zstream_usage();
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}
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}
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