ZFS overhead calc.xlsx

	A	B	C	D	E	F	G	H	I	J	K	L	M	N	O	P
1	total disks	data disks	raidz level	recordsize (KiB)	recordsize (bytes)	ashift	sector size (bytes)	sectors	theoretical sectors per disk	full stripes	partial stripe sectors	total theoretical sectors	total actual sectors	allocation padding	allocation overhead % (before ZFS copy-on-write reservation, AKA slop_shift)

2					128KiB records											Hover here for a walkthrough of the calculation
3	4	2	2	128	131072	12	4096	32	16	16	0	64	64	66	3.13%
4	5	3	2	128	131072	12	4096	32	10.66666667	10	2	53.33333333	54	54	1.25%
5	6	4	2	128	131072	12	4096	32	8	8	0	48	48	48	0.00%
6	7	5	2	128	131072	12	4096	32	6.4	6	2	44.8	46	48	7.14%
7	8	6	2	128	131072	12	4096	32	5.333333333	5	2	42.66666667	44	45	5.47%
8	9	7	2	128	131072	12	4096	32	4.571428571	4	4	41.14285714	42	42	2.08%
9	10	8	2	128	131072	12	4096	32	4	4	0	40	40	42	5.00%
10	11	9	2	128	131072	12	4096	32	3.555555556	3	5	39.11111111	40	42	7.39%
11	12	10	2	128	131072	12	4096	32	3.2	3	2	38.4	40	42	9.37%
12	13	11	2	128	131072	12	4096	32	2.909090909	2	10	37.81818182	38	39	3.13%
13	14	12	2	128	131072	12	4096	32	2.666666667	2	8	37.33333333	38	39	4.46%
14	15	13	2	128	131072	12	4096	32	2.461538462	2	6	36.92307692	38	39	5.62%
15	16	14	2	128	131072	12	4096	32	2.285714286	2	4	36.57142857	38	39	6.64%
16	17	15	2	128	131072	12	4096	32	2.133333333	2	2	36.26666667	38	39	7.54%
17	18	16	2	128	131072	12	4096	32	2	2	0	36	36	36	0.00%
18	19	17	2	128	131072	12	4096	32	1.882352941	1	15	35.76470588	36	36	0.66%
19	20	18	2	128	131072	12	4096	32	1.777777778	1	14	35.55555556	36	36	1.25%
20	21	19	2	128	131072	12	4096	32	1.684210526	1	13	35.36842105	36	36	1.79%
21	22	20	2	128	131072	12	4096	32	1.6	1	12	35.2	36	36	2.27%
22	23	21	2	128	131072	12	4096	32	1.523809524	1	11	35.04761905	36	36	2.72%
23	24	22	2	128	131072	12	4096	32	1.454545455	1	10	34.90909091	36	36	3.13%
24
25					1MiB records
26	4	2	2	1024	1048576	12	4096	256	128	128	0	512	512	513	0.20%
27	5	3	2	1024	1048576	12	4096	256	85.33333333	85	1	426.6666667	428	429	0.55%
28	6	4	2	1024	1048576	12	4096	256	64	64	0	384	384	384	0.00%
29	7	5	2	1024	1048576	12	4096	256	51.2	51	1	358.4	360	360	0.45%
30	8	6	2	1024	1048576	12	4096	256	42.66666667	42	4	341.3333333	342	342	0.20%
31	9	7	2	1024	1048576	12	4096	256	36.57142857	36	4	329.1428571	330	330	0.26%
32	10	8	2	1024	1048576	12	4096	256	32	32	0	320	320	321	0.31%
33	11	9	2	1024	1048576	12	4096	256	28.44444444	28	4	312.8888889	314	315	0.67%
34	12	10	2	1024	1048576	12	4096	256	25.6	25	6	307.2	308	309	0.59%
35	13	11	2	1024	1048576	12	4096	256	23.27272727	23	3	302.5454545	304	306	1.14%
36	14	12	2	1024	1048576	12	4096	256	21.33333333	21	4	298.6666667	300	300	0.45%
37	15	13	2	1024	1048576	12	4096	256	19.69230769	19	9	295.3846154	296	297	0.55%
38	16	14	2	1024	1048576	12	4096	256	18.28571429	18	4	292.5714286	294	294	0.49%
39	17	15	2	1024	1048576	12	4096	256	17.06666667	17	1	290.1333333	292	294	1.33%
40	18	16	2	1024	1048576	12	4096	256	16	16	0	288	288	288	0.00%
41	19	17	2	1024	1048576	12	4096	256	15.05882353	15	1	286.1176471	288	288	0.66%
42	20	18	2	1024	1048576	12	4096	256	14.22222222	14	4	284.4444444	286	288	1.25%
43	21	19	2	1024	1048576	12	4096	256	13.47368421	13	9	282.9473684	284	285	0.73%
44	22	20	2	1024	1048576	12	4096	256	12.8	12	16	281.6	282	282	0.14%
45	23	21	2	1024	1048576	12	4096	256	12.19047619	12	4	280.3809524	282	282	0.58%
46	24	22	2	1024	1048576	12	4096	256	11.63636364	11	14	279.2727273	280	282	0.98%
47
48					128KiB records		ashift=9
49	4	2	2	128	131072	9	512	256	128	128	0	512	512	513	0.20%
50	5	3	2	128	131072	9	512	256	85.33333333	85	1	426.6666667	428	429	0.55%
51	6	4	2	128	131072	9	512	256	64	64	0	384	384	384	0.00%
52	7	5	2	128	131072	9	512	256	51.2	51	1	358.4	360	360	0.45%
53	8	6	2	128	131072	9	512	256	42.66666667	42	4	341.3333333	342	342	0.20%
54	9	7	2	128	131072	9	512	256	36.57142857	36	4	329.1428571	330	330	0.26%
55	10	8	2	128	131072	9	512	256	32	32	0	320	320	321	0.31%
56	11	9	2	128	131072	9	512	256	28.44444444	28	4	312.8888889	314	315	0.67%
57	12	10	2	128	131072	9	512	256	25.6	25	6	307.2	308	309	0.59%
58	13	11	2	128	131072	9	512	256	23.27272727	23	3	302.5454545	304	306	1.14%
59	14	12	2	128	131072	9	512	256	21.33333333	21	4	298.6666667	300	300	0.45%
60	15	13	2	128	131072	9	512	256	19.69230769	19	9	295.3846154	296	297	0.55%
61	16	14	2	128	131072	9	512	256	18.28571429	18	4	292.5714286	294	294	0.49%
62	17	15	2	128	131072	9	512	256	17.06666667	17	1	290.1333333	292	294	1.33%
63	18	16	2	128	131072	9	512	256	16	16	0	288	288	288	0.00%
64	19	17	2	128	131072	9	512	256	15.05882353	15	1	286.1176471	288	288	0.66%
65	20	18	2	128	131072	9	512	256	14.22222222	14	4	284.4444444	286	288	1.25%
66	21	19	2	128	131072	9	512	256	13.47368421	13	9	282.9473684	284	285	0.73%
67	22	20	2	128	131072	9	512	256	12.8	12	16	281.6	282	282	0.14%
68	23	21	2	128	131072	9	512	256	12.19047619	12	4	280.3809524	282	282	0.58%
69	24	22	2	128	131072	9	512	256	11.63636364	11	14	279.2727273	280	282	0.98%
70
71					512KiB records		ashift=12
72	4	2	2	512	524288	12	4096	128	64	64	0	256	256	258	0.78%
73	5	3	2	512	524288	12	4096	128	42.66666667	42	2	213.3333333	214	216	1.25%
74	6	4	2	512	524288	12	4096	128	32	32	0	192	192	192	0.00%
75	7	5	2	512	524288	12	4096	128	25.6	25	3	179.2	180	180	0.45%
76	8	6	2	512	524288	12	4096	128	21.33333333	21	2	170.6666667	172	174	1.95%
77	9	7	2	512	524288	12	4096	128	18.28571429	18	2	164.5714286	166	168	2.08%
78	10	8	2	512	524288	12	4096	128	16	16	0	160	160	162	1.25%
79	11	9	2	512	524288	12	4096	128	14.22222222	14	2	156.4444444	158	159	1.63%
80	12	10	2	512	524288	12	4096	128	12.8	12	8	153.6	154	156	1.56%
81	13	11	2	512	524288	12	4096	128	11.63636364	11	7	151.2727273	152	153	1.14%
82	14	12	2	512	524288	12	4096	128	10.66666667	10	8	149.3333333	150	150	0.45%
83	15	13	2	512	524288	12	4096	128	9.846153846	9	11	147.6923077	148	150	1.56%
84	16	14	2	512	524288	12	4096	128	9.142857143	9	2	146.2857143	148	150	2.54%
85	17	15	2	512	524288	12	4096	128	8.533333333	8	8	145.0666667	146	147	1.33%
86	18	16	2	512	524288	12	4096	128	8	8	0	144	144	144	0.00%
87	19	17	2	512	524288	12	4096	128	7.529411765	7	9	143.0588235	144	144	0.66%
88	20	18	2	512	524288	12	4096	128	7.111111111	7	2	142.2222222	144	144	1.25%
89	21	19	2	512	524288	12	4096	128	6.736842105	6	14	141.4736842	142	144	1.79%
90	22	20	2	512	524288	12	4096	128	6.4	6	8	140.8	142	144	2.27%
91	23	21	2	512	524288	12	4096	128	6.095238095	6	2	140.1904762	142	144	2.72%
92	24	22	2	512	524288	12	4096	128	5.818181818	5	18	139.6363636	140	141	0.98%
93
94					512KiB records		ashift=9
95	4	2	2	512	524288	9	512	1024	512	512	0	2048	2048	2049	0.05%
96	5	3	2	512	524288	9	512	1024	341.3333333	341	1	1706.666667	1708	1710	0.20%
97	6	4	2	512	524288	9	512	1024	256	256	0	1536	1536	1536	0.00%
98	7	5	2	512	524288	9	512	1024	204.8	204	4	1433.6	1434	1434	0.03%
99	8	6	2	512	524288	9	512	1024	170.6666667	170	4	1365.333333	1366	1368	0.20%
100	9	7	2	512	524288	9	512	1024	146.2857143	146	2	1316.571429	1318	1320	0.26%