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	3.125
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
6	7	5	2	128	131072	12	4096	32	6.4	6	2	44.8	46	48	7.142857143
7	8	6	2	128	131072	12	4096	32	5.333333333	5	2	42.66666667	44	45	5.46875
8	9	7	2	128	131072	12	4096	32	4.571428571	4	4	41.14285714	42	42	2.083333333
9	10	8	2	128	131072	12	4096	32	4	4	0	40	40	42	5
10	11	9	2	128	131072	12	4096	32	3.555555556	3	5	39.11111111	40	42	7.386363636
11	12	10	2	128	131072	12	4096	32	3.2	3	2	38.4	40	42	9.375
12	13	11	2	128	131072	12	4096	32	2.909090909	2	10	37.81818182	38	39	3.125
13	14	12	2	128	131072	12	4096	32	2.666666667	2	8	37.33333333	38	39	4.464285714
14	15	13	2	128	131072	12	4096	32	2.461538462	2	6	36.92307692	38	39	5.625
15	16	14	2	128	131072	12	4096	32	2.285714286	2	4	36.57142857	38	39	6.640625
16	17	15	2	128	131072	12	4096	32	2.133333333	2	2	36.26666667	38	39	7.536764706
17	18	16	2	128	131072	12	4096	32	2	2	0	36	36	36	0
18	19	17	2	128	131072	12	4096	32	1.882352941	1	15	35.76470588	36	36	0.6578947368
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	1.785714286
21	22	20	2	128	131072	12	4096	32	1.6	1	12	35.2	36	36	2.272727273
22	23	21	2	128	131072	12	4096	32	1.523809524	1	11	35.04761905	36	36	2.717391304
23	24	22	2	128	131072	12	4096	32	1.454545455	1	10	34.90909091	36	36	3.125
24
25					1MiB records
26	4	2	2	1024	1048576	12	4096	256	128	128	0	512	512	513	0.1953125
27	5	3	2	1024	1048576	12	4096	256	85.33333333	85	1	426.6666667	428	429	0.546875
28	6	4	2	1024	1048576	12	4096	256	64	64	0	384	384	384	0
29	7	5	2	1024	1048576	12	4096	256	51.2	51	1	358.4	360	360	0.4464285714
30	8	6	2	1024	1048576	12	4096	256	42.66666667	42	4	341.3333333	342	342	0.1953125
31	9	7	2	1024	1048576	12	4096	256	36.57142857	36	4	329.1428571	330	330	0.2604166667
32	10	8	2	1024	1048576	12	4096	256	32	32	0	320	320	321	0.3125
33	11	9	2	1024	1048576	12	4096	256	28.44444444	28	4	312.8888889	314	315	0.6747159091
34	12	10	2	1024	1048576	12	4096	256	25.6	25	6	307.2	308	309	0.5859375
35	13	11	2	1024	1048576	12	4096	256	23.27272727	23	3	302.5454545	304	306	1.141826923
36	14	12	2	1024	1048576	12	4096	256	21.33333333	21	4	298.6666667	300	300	0.4464285714
37	15	13	2	1024	1048576	12	4096	256	19.69230769	19	9	295.3846154	296	297	0.546875
38	16	14	2	1024	1048576	12	4096	256	18.28571429	18	4	292.5714286	294	294	0.48828125
39	17	15	2	1024	1048576	12	4096	256	17.06666667	17	1	290.1333333	292	294	1.332720588
40	18	16	2	1024	1048576	12	4096	256	16	16	0	288	288	288	0
41	19	17	2	1024	1048576	12	4096	256	15.05882353	15	1	286.1176471	288	288	0.6578947368
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	0.7254464286
44	22	20	2	1024	1048576	12	4096	256	12.8	12	16	281.6	282	282	0.1420454545
45	23	21	2	1024	1048576	12	4096	256	12.19047619	12	4	280.3809524	282	282	0.5774456522
46	24	22	2	1024	1048576	12	4096	256	11.63636364	11	14	279.2727273	280	282	0.9765625
47
48					128KiB records		ashift=9
49	4	2	2	128	131072	9	512	256	128	128	0	512	512	513	0.1953125
50	5	3	2	128	131072	9	512	256	85.33333333	85	1	426.6666667	428	429	0.546875
51	6	4	2	128	131072	9	512	256	64	64	0	384	384	384	0
52	7	5	2	128	131072	9	512	256	51.2	51	1	358.4	360	360	0.4464285714
53	8	6	2	128	131072	9	512	256	42.66666667	42	4	341.3333333	342	342	0.1953125
54	9	7	2	128	131072	9	512	256	36.57142857	36	4	329.1428571	330	330	0.2604166667
55	10	8	2	128	131072	9	512	256	32	32	0	320	320	321	0.3125
56	11	9	2	128	131072	9	512	256	28.44444444	28	4	312.8888889	314	315	0.6747159091
57	12	10	2	128	131072	9	512	256	25.6	25	6	307.2	308	309	0.5859375
58	13	11	2	128	131072	9	512	256	23.27272727	23	3	302.5454545	304	306	1.141826923
59	14	12	2	128	131072	9	512	256	21.33333333	21	4	298.6666667	300	300	0.4464285714
60	15	13	2	128	131072	9	512	256	19.69230769	19	9	295.3846154	296	297	0.546875
61	16	14	2	128	131072	9	512	256	18.28571429	18	4	292.5714286	294	294	0.48828125
62	17	15	2	128	131072	9	512	256	17.06666667	17	1	290.1333333	292	294	1.332720588
63	18	16	2	128	131072	9	512	256	16	16	0	288	288	288	0
64	19	17	2	128	131072	9	512	256	15.05882353	15	1	286.1176471	288	288	0.6578947368
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	0.7254464286
67	22	20	2	128	131072	9	512	256	12.8	12	16	281.6	282	282	0.1420454545
68	23	21	2	128	131072	9	512	256	12.19047619	12	4	280.3809524	282	282	0.5774456522
69	24	22	2	128	131072	9	512	256	11.63636364	11	14	279.2727273	280	282	0.9765625
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