>  В остальном ничем принципиально не лучше и не хуже KVM.

Ога, щаз... Суслика видишь? -Нет,... - А он есть!

Citrix - нет! Оно куплено EMC (для всех это публичный альянс).
EMC еще купило VMware!  

Вот краткий список патентов на виртуализацию, которых не будет в опенсоурсе ещё лет 10.

VMware, Inc. All rights reserved. VMware software products are protected by one or more U.S. Patent Numbers
D617,808, D617,809, D617,810, D617,811, 6,256,637, 6,360,219, 6,397,242, 6,496,847, 6,567,905, 6,681,226, 6,704,925, 6,711,672, 6,725,289, 6,735,601, 6,785,886, 6,789,156, 6,795,966, 6,880,022, 6,883,095, 6,940,980, 6,944,699, 6,961,806, 6,961,941, 6,970,562, 7,017,041, 7,055,032, 7,065,642, 7,069,413, 7,069,435, 7,082,598, 7,089,377, 7,111,086, 7,111,145, 7,117,481, 7,149,310, 7,149,843, 7,155,558, 7,222,221, 7,260,815, 7,260,820, 7,269,683, 7,275,136, 7,277,998, 7,277,999, 7,278,030, 7,281,102, 7,290,253, 7,343,599, 7,356,679, 7,373,355, 7,386,720, 7,409,487, 7,412,492, 7,412,702, 7,424,710, 7,428,636, 7,433,951, 7,434,002, 7,447,854, 7,447,903, 7,467,067, 7,475,002, 7,478,173, 7,478,180, 7,478,218, 7,478,388, 7,484,208, 7,487,313, 7,487,314, 7,490,216, 7,500,048, 7,506,122, 7,516,453, 7,529,897, 7,555,747, 7,565,527, 7,571,471, 7,577,722, 7,581,064, 7,590,715, 7,590,982, 7,594,111, 7,596,594, 7,596,697, 7,599,493, 7,603,704, 7,606,868, 7,620,523, 7,620,766, 7,620,955, 7,624,240, 7,630,493, 7,636,831, 7,657,659, 7,657,937, 7,665,088, 7,672,814, 7,680,919, 7,693,996, 7,694,101, 7,702,843, 7,707,185, 7,707,285, 7,707,578, 7,716,446, 7,734,045, 7,734,911, 7,734,912, 7,735,136, 7,743,389, 7,761,917, 7,765,543, 7,774,391, 7,779,091, 7,783,779, 7,783,838, 7,793,279, 7,797,748, 7,801,703, 7,802,000, 7,802,248, 7,805,676, 7,814,495, 7,823,145, 7,831,661, 7,831,739, 7,831,761, 7,831,773, 7,840,790, 7,840,839, 7,840,993, 7,844,954, 7,849,098, 7,853,744, 7,853,960, 7,856,419, 7,856,531, 7,856,637, 7,865,663, 7,869,967, 7,886,127, 7,886,148, 7,886,346, 7,890,754, 7,895,437, 7,908,646, 7,912,951, 7,921,197, 7,925,850, 7,933,981, 7,934,017, 7,934,020, 7,941,470, 7,941,827, 7,945,436, 7,945,761, 7,945,908, 7,945,958, 7,953,833, 7,958,558, 7,962,647, 7,966,615, 7,970,938, 7,971,015, 7,971,047, 7,971,182, 7,975,165, 7,984,254, 7,984,264, 7,984,304, 8,001,083, 8,001,322, 8,006,043, 8,010,667, 8,010,676, 8,010,701, 8,013,859, 8,015,367, 8,015,388, 8,019,861, 8,024,506, 8,024,779, 8,028,071, 8,037,032, 8,037,227, 8,037,280, 8,046,468, 8,056,076, 8,060,342, 8,060,722, 8,060,875, 8,060,877, 8,060,883, 8,069,250, 8,074,045, 8,086,822, 8,095,525, 8,095,929, 8,095,931, 8,099,568, 8,099,607, 8,112,505, 8,117,410, 8,127,014, 8,127,107, 8,127,301, 8,141,075, 8,141,163, 8,145,752, 8,145,763, 8,145,836, 8,146,082, 8,151,263, 8,166,107, 8,166,211, 8,166,253, 8,166,349, 8,166,474, 8,166,475, 8,166,554, 8,170,123, 8,171,033, 8,171,140, 8,171,141, 8,171,142, 8,171,278, 8,171,338, 8,171,345, 8,171,482, 8,171,485, 8,171,488, 8,171,548, 8,176,493, 8,195,774, 8,195,866, 8,201,169, 8,204,986, 8,209,343, 8,209,408, 8,209,680, 8,213,608, 8,214,522, 8,214,576, 8,214,802, 8,214,875, 8,219,063, 8,219,779, 8,219,987, 8,225,071, 8,233,882, 8,234,518, 8,239,608, 8,239,646, 8,239,655, 8,244,853, 8,245,081, 8,245,129, 8,245,227, 8,250,197, 8,250,214, 8,250,519, 8,250,586, 8,250,638, 8,255,484, 8,255,806, 8,260,816, 8,260,904, 8,261,265, 8,266,099, 8,266,275, 8,266,279, 8,266,395, 8,266,404, 8,266,628, 8,271,450, 8,275,563, 8,281,318, 8,281,377, 8,286,174, 8,291,135, 8,291,159, 8,291,180, 8,291,436, 8,295,308, 8,296,472, 8,296,551, 8,296,759, 8,296,767, 8,301,874, 8,302,094, 8,307,187, 8,307,191, 8,307,192, 8,312,175, 8,312,471, 8,312,522, 8,316,193, 8,316,374, 8,321,643, 8,321,842, 8,321,850, 8,327,059, 8,332,921, 8,335,703, 8,336,049, 8,340,287, 8,341,749, 8,347,263, 8,347,344, 8,352,240, 8,352,482, 8,352,490, 8,352,705, 8,352,944, 8,359,374, 8,359,422, 8,359,451, 8,359,593, 8,364,932, 8,380,747, 8,380,939, 8,392,361, 8,392,838, 8,397,038, 8,402,224, 8,402,441, 8,402,527, 8,407,475, 8,407,518, 8,412,910, 8,417,812, 8,429,647, 8,429,665, 8,438,430, 8,441,494, 8,443,139, 8,443,156, 8,443,166, 8,443,261, 8,443,367, 8,448,022, 8,453,108, 8,453,143, 8,458,318, 8,458,329, 8,463,730, 8,463,905, 8,464,022, 8,464,259, 8,468,310, 8,473,946, 8,473,947, 8,478,725, 8,478,801, 8,478,924, 8,479,195, 8,543,781, 8,543,790, 8,544,010, 8,484,405, 8,489,636, 8,489,699, 8,489,719, 8,489,800, 8,490,085, 8,495,631, 8,498,987, 8,499,004, 8,499,297, 8,510,438, 8,510,590, 8,510,827, 8,521,504, 8,521,686, 8,521,666, 8,522,228, 8,527,673, 8,528,107, 8,533,382, 8,553,745, 8,543,781, 8,543,790, 8,544,010, 8,549,241, 8,549,364, 8,554,900, 8,554,981, 8,555,003, 8,555,081, 8,555,274, 8,560,577, 8,560,626, 8,560,747, 8,560,791, 8,561,061, 8,566,502, 8,566,744, 8,572,606, 8,572,608, 8,577,853, 8,577,937, 8,578,083, 8,578,380, 8, 583,875, 8,584,126, 8,589,913, 8,589,940, 8,595,369, 8,595,460, 8,595,487, 8,595,824, 8,607,011, 8,607,013, 8,612,659, 8,615,489, 8,619,771, 8,621,136, 8,621,607, 8,626,723, 8,631,065, 8,631,066, 8,631,117, 8,631,403, 8,635,330, 8,635,395, 8635,493, 8,639,917, 8,640,126, 8,650,359, 8,650,566, 8,650,564, 8,656,000, 8,655,971, 8,656,222, 8,656,389, 8,656,497, 8,661,182, 8,661,213, 8,661,428, 8,666,938, 8,667,187, 8,667,459, 8,667,500, 8,671,238, 8,677,085, 8,667,187, 8,677,351, 8,667,352, 8,683,041, 8,683,466, 8,688,823, 8,694,713, 8,694,728, 8,694,746 8,694,828, 8,700,585, 8,700,611, 8,701,107, 8,706,991, 8,707,035, 8,712,960, 8,713,273, 8,713,646, 8,717,895, 8,718,070, 8,719,401, 8,719,513, 8,719,545, 8,719,661, 8,719,800, 8,719,817, 8,719,823, 8,724,696, 8,725,886, 8,726,273, 8,726,225, 8,732,313, 8,732,700, 8,738,333, 8,738,868, 8,743,888, 8,743,889, 8,745,236, 8,745,241, 8,745,308, 8,745,336, 8,745,351, 8,750,119, 8,750,164, 8,751,867, 8,752,058, 8,756,397, 8,756,426, 8,763,115, 8,761,036, 8,762,660, 8,762,684, 8,769,174, 8,769,184, 8,775,594, 8,775,696, 8,775,748, 8,775,773, 8,775,774, 8,775,815, 8,775,903, 8,776,055, 8,776,089, 8,782,242, 8,782,310, 8,782,768, 8,788,079, 8,789,049, 8,793,428, 8,798,541, 8,799,418, 8,799,897, 8,799,921, 8,880,018, 8,805,934, 8,806,217, 8,806,484, 8,812,876, 8,813,074, 8,819,357, 8,817,620, 8,817,621, 8,819,674, 8,819,676, 8,819,822, 8,825,851, 8,825,909, 8,826,273, 8,826,278, 8,826,283, 8,826,289, 8,826,432, 8,825,994, 8,830,823, 8,830, 8,358,832,351, 8,832,390, 8,832,682, 8,832,785, 8,837,493, 8,839,201, 8,839,202, 8,839,266, 8,839,914, 8,838,756, 8,842,679, 8,843,933, 8,843,935, 8,850,004, 8,856,784, 8,862,695, 8,862,868, 8,863,127, 8,868,610, 8,868,880, 8,869,139, 8,874,744, 8,874,859, 8,875,162, 8,875,266, 8,875,288, 8,874,802, 8,874,803, 8,880,468, 8,880,470, 8,880,774, 8,880,930, 8,881,143, 8,886,708, 8,886,865, 8,892,737, 8,892,706, 8,892,776, 8,893,261, 8,892,716, 8,892,706, 8,892,716, 8,892,737, 8,892,776, 8,893,261, 8,898,108, 8,898,676, 8,898,508, 8,898,509, 8,898,518, 8,902,248, 8,902,242, 8,904,081, 8,910,297, 8,909,602, 8,909,928, 8,910,161, 8,910,228, 8,913,483, 8,913,611, 8,914,013, 8,914,567, 8,914,575, 8,914,598, 8,914,610, 8,914,684, 8,914,730, 8,917,617, 8,924,524, 8,924,534, 8,924,608, 8,924,967, 8,924,970, 8,925,036, 8,929,287, 8,930,592, 8,930,812, 8,930,948, 8,935,429, 8,935,456, 8,935,500, 8,938,680, 8,943,259, 8,943,296, 8,949,295, 8,949,399, 8,949,531, 8,949,546, 8,949,570, 8,949,585, 8,949,731, 8,949,791, 8,849,794, 8,949,817, 8,954,050, 8,954,387, 8,954,545, 8,954,575, 8,954,665, 8,955,072, 8,955,151, 8,958,292, 8,958,298, 8,959,215, 8,959,312, 8,959,338, 8,959,529, 8,964,528, 8,964,598, 8,964,767, 8,966,024, 8,966,029, 8,966,035, 8,966,040, 8,966,479, 8,966,581, 8,966,623, 8,972,981, 8,977,702, 8,977,736, 8,978,053, 8,978,110, 8,983,988, 8,984,508, 8,990,531, 8,990,699, 8,995,763, 8,996,853, 8,996,884, 8,997,187, 9,003,027, 9,003,037, 9,007,903, 9,008,087, 9,009,219, 9,009,727, 9,007,903, 9,008,087, 9,009,727, 9,015,180, 9,015,203, 9,015,823, 9,019,826, 9,019,977, 9,021,037, 9,026,510, 9,026,613, 9,026,630, 9,027,003, 9,027,031, 9,031,894, 9,032,050, 9,032,133, 9,032,170, 9,032,176, 9,032,181, 9,032,398, 9,032,402, 9,032,425, 9,037,522, 9,037,556, 9,037,621, 9,037,689, 9,037,719, 9,037,758, 9,037,873, 9,038,066, 9,042,304, 9,043,452, 9,043,792, 9,047,083, 9,047,087, 9,047,133, 9,049,153, 9,049,193, 9,049,257, 9,052,825, 9,052,937, 9,052,949, 9,052,961, 9,052,967, 9,053,064, 9,053,065, 9,054,995, 9,055,119, 9,058,232, 9,058,259, 9,058,353, 9,058,420, 9,058,495, 9,059,964, 9,059,989, 9,059,999, 9,063,756, 9,063,762, 9,063,766, 9,063,768, 9,063,866, 9,064,447, 9,069,579, 9,069,600, 9,069,607, 9,069,608, 9,069,902 , 9,075,718, 9,075,731, 9,077,664, 9,077,725, 9,081,536, 9,081,622, 9,081,686, 9,081,722, 9,083,606, 9,086,904, 9,086,921, 9,086,981, 9,087,191, 9,088,591, 9,092,318, 9,094,413, 9,097,528, 9,098,318, 9,098,347, 9,098,457, 9,099,974, 9,100,293, 9,104,402, 9,104, 469, 9,106,587, 9,116,726, 9,116,829, 9,116,737, 9,116,903, 9,122,594, 9,122,765, 9,123,031, 9,124,488, 9,124,538, 9,128,746, 9,129,062, 9,130,821, 9,130,879, 9,134,922, 9,134,992, 9,135,050, 9,135,171, 9,135,287, 9,135,342, 9,135,457, 9,137,052, 9,137,107, 9,137,222, 9,141,444, 9,141,578, 9,142,004, 9,141,381;

:)

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Ну например опенсоурсная шняжка не умеет:

запускать 64-битные системы на 32-битных процах.
копипасту мышом и клавой
расшареные фолдеры (только самба/нфс/plan9/fuse/черезшопа/...)
почти нулевая поддержка графики (долго рассказывать). например 1280x1024 при 24 битах цвета, с полно экранной графикой выдаёт 6 fps.  

А ещё KVM от балды вырубится может, похерить образ, забыть дописать commit в клон,....  

В общем, KVM - ковно полное, годное только для изоляции малонагруженных LAMP и начёсу ЧСВ одминов локалхостов.