这个问题是关于压缩相当大的数据目录（大约 22-23 GiB），特别是此类档案的完整性检查。我大约每月一次进行这些大型备份，因此所花费的时间在这里不是问题。
我使用的是基于 Ubuntu 18.04 的 Linux Mint 19.1，我想与可用的最佳校验和或验证tar结合使用。xz
供将来参考的软件版本：
$ tar --version
tar (GNU tar) 1.29
和
$ xz --version
xz (XZ Utils) 5.2.2
只是要注意：
我把它烧了M盘媒体。
我不介意花很长时间；我强调这一点。
如果某些设置取决于内存，那么我在这台笔记本电脑中配备了 16 GiB DDR4。
在我看来，根据xz 手册页，我看没有办法设置固体压缩这可能有助于提高压缩率。
直到今天，我只是使用最简单的方法一次性完成蓝光备份：
$ tar -cJf ...
它相对较快，但在压缩一些.iso文件时几乎没有发生压缩，这些文件已经在里面压缩了，而且我仍然有关于增加的问题，......好吧，更好的词是确保我的档案的完整性。
在...的帮助下：
$ xz -l ...
我能够对输出结果进行一些分析+我发现 CRC-64 已作为校验和方法就位。
现在在写这篇文章时，我发现了一种有趣的方式来指定压缩级别，当然不是设置为最大（9），也不极端默认情况下：
$ XZ_OPT=-9e tar ...
我还发现我可以将xz校验和从默认的 CRC-64 切换为 SHA-256：
$ XZ_OPT='-9 --extreme --check=sha256' tar ...
我现在想知道的是--verify的tar选项手册页:
写入后尝试验证存档
因为如果如上所示一次性执行此操作，添加此选项会导致：
tar: Cannot verify compressed archives
相反，我必须做类似的事情：
$ tar --create --file="${backup_file}" "${dir_to_backup}" --verify
xz并与事后单独归档；我不确定如何直接使用它？
^^^ 这是我的问题 ^^^
示例存档几乎不可能进行压缩，因为它的所有内容都已被压缩并包含在.iso文件中。不过，我通过压缩获得了 1.8 GiB，这很好。
$ xz --list backup--2019-03-09.tar.xz
backup--2019-03-09.tar.xz (1/1)
Streams: 1
Blocks: 127
Compressed size: 22.0 GiB (23,670,187,308 B)
Uncompressed size: 23.8 GiB (25,546,864,640 B)
Ratio: 0.927
Check: SHA-256
Stream padding: 0 B
Streams:
Stream Blocks CompOffset UncompOffset CompSize UncompSize Ratio Check Padding
1 127 0 0 23,670,187,308 25,546,864,640 0.927 SHA-256 0
Blocks:
Stream Block CompOffset UncompOffset TotalSize UncompSize Ratio Check
1 1 12 0 53,243,880 201,326,592 0.264 SHA-256
1 2 53,243,892 201,326,592 196,992,880 201,326,592 0.978 SHA-256
1 3 250,236,772 402,653,184 201,315,216 201,326,592 1.000 SHA-256
1 4 451,551,988 603,979,776 201,335,864 201,326,592 1.000 SHA-256
1 5 652,887,852 805,306,368 201,335,864 201,326,592 1.000 SHA-256
1 6 854,223,716 1,006,632,960 201,334,900 201,326,592 1.000 SHA-256
1 7 1,055,558,616 1,207,959,552 200,622,316 201,326,592 0.997 SHA-256
1 8 1,256,180,932 1,409,286,144 201,335,832 201,326,592 1.000 SHA-256
1 9 1,457,516,764 1,610,612,736 201,335,864 201,326,592 1.000 SHA-256
1 10 1,658,852,628 1,811,939,328 201,330,732 201,326,592 1.000 SHA-256
1 11 1,860,183,360 2,013,265,920 199,713,948 201,326,592 0.992 SHA-256
1 12 2,059,897,308 2,214,592,512 175,761,000 201,326,592 0.873 SHA-256
1 13 2,235,658,308 2,415,919,104 201,165,620 201,326,592 0.999 SHA-256
1 14 2,436,823,928 2,617,245,696 201,321,784 201,326,592 1.000 SHA-256
1 15 2,638,145,712 2,818,572,288 201,326,148 201,326,592 1.000 SHA-256
1 16 2,839,471,860 3,019,898,880 200,038,544 201,326,592 0.994 SHA-256
1 17 3,039,510,404 3,221,225,472 200,750,292 201,326,592 0.997 SHA-256
1 18 3,240,260,696 3,422,552,064 201,310,636 201,326,592 1.000 SHA-256
1 19 3,441,571,332 3,623,878,656 201,335,864 201,326,592 1.000 SHA-256
1 20 3,642,907,196 3,825,205,248 201,335,864 201,326,592 1.000 SHA-256
1 21 3,844,243,060 4,026,531,840 201,335,864 201,326,592 1.000 SHA-256
1 22 4,045,578,924 4,227,858,432 201,335,864 201,326,592 1.000 SHA-256
1 23 4,246,914,788 4,429,185,024 201,330,168 201,326,592 1.000 SHA-256
1 24 4,448,244,956 4,630,511,616 199,487,940 201,326,592 0.991 SHA-256
1 25 4,647,732,896 4,831,838,208 201,335,172 201,326,592 1.000 SHA-256
1 26 4,849,068,068 5,033,164,800 201,334,468 201,326,592 1.000 SHA-256
1 27 5,050,402,536 5,234,491,392 201,170,860 201,326,592 0.999 SHA-256
1 28 5,251,573,396 5,435,817,984 201,200,520 201,326,592 0.999 SHA-256
1 29 5,452,773,916 5,637,144,576 191,043,588 201,326,592 0.949 SHA-256
1 30 5,643,817,504 5,838,471,168 196,939,368 201,326,592 0.978 SHA-256
1 31 5,840,756,872 6,039,797,760 185,189,612 201,326,592 0.920 SHA-256
1 32 6,025,946,484 6,241,124,352 201,298,652 201,326,592 1.000 SHA-256
1 33 6,227,245,136 6,442,450,944 201,137,020 201,326,592 0.999 SHA-256
1 34 6,428,382,156 6,643,777,536 201,166,576 201,326,592 0.999 SHA-256
1 35 6,629,548,732 6,845,104,128 201,230,404 201,326,592 1.000 SHA-256
1 36 6,830,779,136 7,046,430,720 201,265,840 201,326,592 1.000 SHA-256
1 37 7,032,044,976 7,247,757,312 201,277,512 201,326,592 1.000 SHA-256
1 38 7,233,322,488 7,449,083,904 201,252,812 201,326,592 1.000 SHA-256
1 39 7,434,575,300 7,650,410,496 201,268,876 201,326,592 1.000 SHA-256
1 40 7,635,844,176 7,851,737,088 201,220,980 201,326,592 0.999 SHA-256
1 41 7,837,065,156 8,053,063,680 201,286,716 201,326,592 1.000 SHA-256
1 42 8,038,351,872 8,254,390,272 201,162,416 201,326,592 0.999 SHA-256
1 43 8,239,514,288 8,455,716,864 201,167,132 201,326,592 0.999 SHA-256
1 44 8,440,681,420 8,657,043,456 201,191,296 201,326,592 0.999 SHA-256
1 45 8,641,872,716 8,858,370,048 201,234,228 201,326,592 1.000 SHA-256
1 46 8,843,106,944 9,059,696,640 201,300,992 201,326,592 1.000 SHA-256
1 47 9,044,407,936 9,261,023,232 198,262,448 201,326,592 0.985 SHA-256
1 48 9,242,670,384 9,462,349,824 91,113,148 201,326,592 0.453 SHA-256
1 49 9,333,783,532 9,663,676,416 143,398,764 201,326,592 0.712 SHA-256
1 50 9,477,182,296 9,865,003,008 178,570,780 201,326,592 0.887 SHA-256
1 51 9,655,753,076 10,066,329,600 188,475,820 201,326,592 0.936 SHA-256
1 52 9,844,228,896 10,267,656,192 193,534,136 201,326,592 0.961 SHA-256
1 53 10,037,763,032 10,468,982,784 157,357,336 201,326,592 0.782 SHA-256
1 54 10,195,120,368 10,670,309,376 111,495,992 201,326,592 0.554 SHA-256
1 55 10,306,616,360 10,871,635,968 99,397,052 201,326,592 0.494 SHA-256
1 56 10,406,013,412 11,072,962,560 192,862,268 201,326,592 0.958 SHA-256
1 57 10,598,875,680 11,274,289,152 180,224,836 201,326,592 0.895 SHA-256
1 58 10,779,100,516 11,475,615,744 165,539,672 201,326,592 0.822 SHA-256
1 59 10,944,640,188 11,676,942,336 170,200,512 201,326,592 0.845 SHA-256
1 60 11,114,840,700 11,878,268,928 130,293,232 201,326,592 0.647 SHA-256
1 61 11,245,133,932 12,079,595,520 194,065,376 201,326,592 0.964 SHA-256
1 62 11,439,199,308 12,280,922,112 187,087,700 201,326,592 0.929 SHA-256
1 63 11,626,287,008 12,482,248,704 187,057,960 201,326,592 0.929 SHA-256
1 64 11,813,344,968 12,683,575,296 187,377,228 201,326,592 0.931 SHA-256
1 65 12,000,722,196 12,884,901,888 199,580,888 201,326,592 0.991 SHA-256
1 66 12,200,303,084 13,086,228,480 152,912,664 201,326,592 0.760 SHA-256
1 67 12,353,215,748 13,287,555,072 169,255,644 201,326,592 0.841 SHA-256
1 68 12,522,471,392 13,488,881,664 187,663,644 201,326,592 0.932 SHA-256
1 69 12,710,135,036 13,690,208,256 194,150,692 201,326,592 0.964 SHA-256
1 70 12,904,285,728 13,891,534,848 193,988,696 201,326,592 0.964 SHA-256
1 71 13,098,274,424 14,092,861,440 195,142,924 201,326,592 0.969 SHA-256
1 72 13,293,417,348 14,294,188,032 200,672,944 201,326,592 0.997 SHA-256
1 73 13,494,090,292 14,495,514,624 199,290,184 201,326,592 0.990 SHA-256
1 74 13,693,380,476 14,696,841,216 199,263,024 201,326,592 0.990 SHA-256
1 75 13,892,643,500 14,898,167,808 183,145,436 201,326,592 0.910 SHA-256
1 76 14,075,788,936 15,099,494,400 167,990,704 201,326,592 0.834 SHA-256
1 77 14,243,779,640 15,300,820,992 196,509,992 201,326,592 0.976 SHA-256
1 78 14,440,289,632 15,502,147,584 147,559,752 201,326,592 0.733 SHA-256
1 79 14,587,849,384 15,703,474,176 183,516,020 201,326,592 0.912 SHA-256
1 80 14,771,365,404 15,904,800,768 135,885,500 201,326,592 0.675 SHA-256
1 81 14,907,250,904 16,106,127,360 182,531,984 201,326,592 0.907 SHA-256
1 82 15,089,782,888 16,307,453,952 165,100,712 201,326,592 0.820 SHA-256
1 83 15,254,883,600 16,508,780,544 161,361,236 201,326,592 0.801 SHA-256
1 84 15,416,244,836 16,710,107,136 201,335,864 201,326,592 1.000 SHA-256
1 85 15,617,580,700 16,911,433,728 199,923,388 201,326,592 0.993 SHA-256
1 86 15,817,504,088 17,112,760,320 193,446,284 201,326,592 0.961 SHA-256
1 87 16,010,950,372 17,314,086,912 198,499,544 201,326,592 0.986 SHA-256
1 88 16,209,449,916 17,515,413,504 201,335,864 201,326,592 1.000 SHA-256
1 89 16,410,785,780 17,716,740,096 201,335,864 201,326,592 1.000 SHA-256
1 90 16,612,121,644 17,918,066,688 201,335,864 201,326,592 1.000 SHA-256
1 91 16,813,457,508 18,119,393,280 201,335,864 201,326,592 1.000 SHA-256
1 92 17,014,793,372 18,320,719,872 201,335,864 201,326,592 1.000 SHA-256
1 93 17,216,129,236 18,522,046,464 201,335,864 201,326,592 1.000 SHA-256
1 94 17,417,465,100 18,723,373,056 201,330,604 201,326,592 1.000 SHA-256
1 95 17,618,795,704 18,924,699,648 201,335,864 201,326,592 1.000 SHA-256
1 96 17,820,131,568 19,126,026,240 183,578,156 201,326,592 0.912 SHA-256
1 97 18,003,709,724 19,327,352,832 201,335,864 201,326,592 1.000 SHA-256
1 98 18,205,045,588 19,528,679,424 201,162,480 201,326,592 0.999 SHA-256
1 99 18,406,208,068 19,730,006,016 201,333,120 201,326,592 1.000 SHA-256
1 100 18,607,541,188 19,931,332,608 199,120,720 201,326,592 0.989 SHA-256
1 101 18,806,661,908 20,132,659,200 201,335,864 201,326,592 1.000 SHA-256
1 102 19,007,997,772 20,333,985,792 201,335,864 201,326,592 1.000 SHA-256
1 103 19,209,333,636 20,535,312,384 201,335,772 201,326,592 1.000 SHA-256
1 104 19,410,669,408 20,736,638,976 201,335,864 201,326,592 1.000 SHA-256
1 105 19,612,005,272 20,937,965,568 179,075,024 201,326,592 0.889 SHA-256
1 106 19,791,080,296 21,139,292,160 128,422,864 201,326,592 0.638 SHA-256
1 107 19,919,503,160 21,340,618,752 186,242,664 201,326,592 0.925 SHA-256
1 108 20,105,745,824 21,541,945,344 199,270,940 201,326,592 0.990 SHA-256
1 109 20,305,016,764 21,743,271,936 198,996,836 201,326,592 0.988 SHA-256
1 110 20,504,013,600 21,944,598,528 175,004,932 201,326,592 0.869 SHA-256
1 111 20,679,018,532 22,145,925,120 200,046,576 201,326,592 0.994 SHA-256
1 112 20,879,065,108 22,347,251,712 178,979,024 201,326,592 0.889 SHA-256
1 113 21,058,044,132 22,548,578,304 199,886,808 201,326,592 0.993 SHA-256
1 114 21,257,930,940 22,749,904,896 177,371,480 201,326,592 0.881 SHA-256
1 115 21,435,302,420 22,951,231,488 190,387,928 201,326,592 0.946 SHA-256
1 116 21,625,690,348 23,152,558,080 194,894,972 201,326,592 0.968 SHA-256
1 117 21,820,585,320 23,353,884,672 199,717,584 201,326,592 0.992 SHA-256
1 118 22,020,302,904 23,555,211,264 152,814,704 201,326,592 0.759 SHA-256
1 119 22,173,117,608 23,756,537,856 199,462,188 201,326,592 0.991 SHA-256
1 120 22,372,579,796 23,957,864,448 175,908,224 201,326,592 0.874 SHA-256
1 121 22,548,488,020 24,159,191,040 181,534,208 201,326,592 0.902 SHA-256
1 122 22,730,022,228 24,360,517,632 195,606,504 201,326,592 0.972 SHA-256
1 123 22,925,628,732 24,561,844,224 192,220,808 201,326,592 0.955 SHA-256
1 124 23,117,849,540 24,763,170,816 188,762,236 201,326,592 0.938 SHA-256
1 125 23,306,611,776 24,964,497,408 173,512,276 201,326,592 0.862 SHA-256
1 126 23,480,124,052 25,165,824,000 106,397,932 201,326,592 0.528 SHA-256
1 127 23,586,521,984 25,367,150,592 83,664,288 179,714,048 0.466 SHA-256