Proofing Fusion Drive on 2012 Mac Mini

[xlii]

I thought it would be fun if we could put our collective heads together and see exactly what happens with the working of fusion drive. If anyone knows the unix command to see how much space we have on the ssd part of fusion drive... post it here. I have 650 GB of space used across my 128 GB samsung 830 and the 1 TB drive. I redid what that ars article did. I started a series 5 GB transfers using the black magic app and in terminal I used the iostat command to see what was happening. Disk0 is the SSD and disk1 is the HDD. It took multiple 5 Gb transfers to get to the HHD. You would think that it would only take one if I truly have only a 4 GB buffer on the SSD. Hope some of you guys can give some insight...

(each line is a 10 second interval)

xlii$ iostat -w 10 -d -I disk0 disk1
disk0 disk1
KB/t xfrs MB KB/t xfrs MB
258.24 2222523 560493.95 141.12 99863 13762.76
6.40 5 0.03 0.00 0 0.00
660.81 2331 1504.25 0.00 0 0.00
649.25 8255 5233.93 0.00 0 0.00
650.68 13707 8709.83 0.00 0 0.00
653.41 18799 11995.58 0.00 0 0.00
652.04 24638 15688.48 0.00 0 0.00
652.06 30455 19393.11 0.00 0 0.00
655.15 35461 22687.89 0.00 0 0.00
655.88 40720 26081.38 0.00 0 0.00
657.18 46418 29790.04 0.00 0 0.00
658.09 52017 33429.62 0.00 0 0.00
658.57 57012 36666.36 0.00 0 0.00
659.32 62435 40200.12 0.00 0 0.00
659.76 68123 43891.64 0.00 0 0.00
660.61 73445 47381.41 0.00 0 0.00
660.70 78477 50634.43 0.00 0 0.00
661.22 84083 54294.56 0.00 0 0.00
661.52 89765 57989.33 0.00 0 0.00
660.48 95061 61314.79 0.00 0 0.00
disk0 disk1
KB/t xfrs MB KB/t xfrs MB
660.80 100182 64649.14 0.00 0 0.00
660.99 105942 68385.10 0.00 0 0.00
660.74 111688 72066.73 0.00 0 0.00
660.44 116806 75335.60 0.00 0 0.00
660.77 122111 78795.64 4.00 1 0.00
660.32 127886 82466.86 4.00 1 0.00
660.50 133655 86209.56 4.00 1 0.00

Now it starts going to the HHD

660.38 137245 88509.71 874.85 136 116.19
659.69 141074 90884.46 875.03 408 348.64
659.68 146076 94105.26 875.10 544 464.89
659.79 151261 97460.88 875.10 544 464.89
659.61 156389 100738.61 873.52 545 464.91
659.91 162245 104558.28 873.52 545 464.91
660.08 168041 108320.51 873.52 545 464.91
659.99 173322 111709.10 873.52 545 464.91
660.34 178320 114991.73 873.52 545 464.91
660.60 184015 118710.79 873.52 545 464.91
660.96 189828 122528.21 873.52 545 464.91
660.80 194308 125388.76 873.52 545 464.91
660.62 199689 128826.74 873.52 545 464.91
disk0 disk1
KB/t xfrs MB KB/t xfrs MB
660.12 205379 132398.25 873.52 545 464.91
653.59 212655 135732.63 871.93 546 464.91
653.89 217347 138789.36 871.93 546 464.91
653.88 222633 142163.88 871.93 546 464.91
654.13 228270 145817.71 871.93 546 464.91
654.54 233336 149147.61 871.93 546 464.91
654.20 238810 152567.20 867.21 549 464.94
654.33 244748 156391.36 867.21 549 464.94
654.29 250706 160190.35 867.21 549 464.94
653.34 256075 163382.81 860.96 553 464.95
648.98 262986 166672.68 853.30 558 464.98
647.76 268824 170051.48 844.28 564 465.02
647.56 273677 173069.86 841.34 566 465.04
647.87 278601 176266.61 818.32 582 465.10
646.72 284514 179688.68 526.39 925 475.50
646.26 290324 183227.37 509.45 956 475.62
645.24 295640 186286.75 486.24 1002 475.80
645.04 301188 189723.51 486.24 1002 475.80
643.89 307596 193417.27 468.22 1041 476.00
643.19 309373 194322.77 378.75 1409 521.15
disk0 disk1
KB/t xfrs MB KB/t xfrs MB
632.66 315774 195095.47 174.63 7576 1292.02
627.12 319123 195438.37 161.84 10312 1629.79
626.93 319222 195440.82 161.46 10340 1630.36
626.93 319224 195440.84 161.46 10340 1630.36
626.59 319408 195445.74 157.83 10618 1636.54
626.22 319607 195451.96 157.83 10618 1636.54
626.15 319639 195452.20 157.83 10618 1636.54
625.94 319752 195453.68 157.79 10621 1636.57
625.90 319772 195453.85 157.79 10621 1636.57
625.65 319901 195455.63 157.79 10621 1636.57
625.13 320173 195460.19 157.77 10622 1636.59
625.08 320203 195460.43 157.77 10622 1636.59
624.93 320285 195463.50 157.77 10622 1636.59
624.64 320433 195464.92 157.76 10623 1636.60
624.64 320433 195464.92 157.76 10623 1636.60
624.64 320436 195464.94 157.76 10623 1636.60
^C
mac-mini-2012:~ xlii$

Killed it with a control c

 

[mogens]

Interesting, but too technical for me. What is "xfrs" etc. ?
I have have a DIY FUD with a Samsung830 256 GB SSD/2TB HDD. Could be interesting to get an analysis of the workflow on apples FUD compared with the DIY FUD on older macs.

 

[xlii]

Interesting, but too technical for me. What is "xfrs" etc. ?
I have have a DIY FUD with a Samsung830 256 GB SSD/2TB HDD. Could be interesting to get an analysis of the workflow on apples FUD compared with the DIY FUD on older macs.

xfrs = transfers... that referred to the number of transfers in Mega Bytes. If anyone knows the unix command so we can see how much space is used on the ssd or the hdd when merged into a fusion drive... point us to it.