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Number of Cylinder on specific disk drive
I'm in the midst of planning the layout for vMAX40k and have a need to find out the total Cylinder number per drive.
With some online posts, it has formula as:
GB = Cylinders * 15 * 128 * 512 / 1024 / 1024 / 1024
Cylinders = GB / 15 / 128 / 512 * 1024 * 1024 * 1024
Given 2 TB drive known/validated number of Cylinder from "symdisk list -cyl" command is "1915210" and EMC published usable space of 2TB(raw) drive is 1882.7GB. I can't seem to match the formula with these two numbers.
Is there anything missing?
The quick and direct question: Anyone has a vMAX system with 600GB 7.2k rpm drive and 100GB EFD, would you mind to run a command "symdisk list -cyl" and post the output here for these two type?
christopher_ime
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October 22nd, 2013 21:00
Please consider moving this question as-is (no need to recreate) to the proper forum for maximum visibility. Questions written to the users' own "Discussions" space don't get the same amount of attention and questions can go unanswered for a long time.
You can do so by selecting "Move" under ACTIONS along the upper-right. Then search for and select: "Symmetrix Support Forum"
AranH1
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October 24th, 2013 15:00
A cylinder is 960KB so a simpler formula is:
GB = Cyl * 960 / 1024 / 1024
Cyl = GB * 1024 * 1024 / 960
The Cylinder count you list for a 2TB drive is accurate as the usable capacity is 1,753GB:
1915210 cyl * 960 / 1024 / 1024 = 1753.4271 GB
A 600GB drive is 586337 cylinders, and a 100GB drive is 100187 cylinders.
The confusion about the 1882GB number comes from using the marketing GB definition which uses decimal (1000MB = 1GB) and the engineering binary definition of GB or GiB (1024MiB = 1GiB).
So to convert the marketing numbers to engineering numbers use:
GB * 1000 * 1000 * 1000 / 1024 / 1024 / 1024 = GiB
1882.72 * 1000 * 1000 * 1000 / 1024 / 1024 / 1024 = 1753.4196
Which is pretty close to our conversion of the cylinders above. You can use the spec sheet below to get the formatted capacities to convert to usable GiB and Cylinders.
http://www.emc.com/collateral/hardware/specification-sheet/h10989-symmetrix-vmax-40k-ss.pdf
bz15_628e6f
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October 24th, 2013 18:00
Thx AranH,
With the formula you provided, I can only get total Cylinder of:
586241 - 600GB
100095 - 100GB
In stead of "A 600GB drive is 586337 cylinders, and a 100GB drive is 100187 cylinders." Anything wrong here?
I had to run into rush before anyone replied this question. So here comes my magic math:
I had the link http://www.emc.com/collateral/hardware/specification-sheet/h10989-symmetrix-vmax-40k-ss.pdf for Usable .vs. marketing capacity matrix.
Because all the math we did are multiplication & division only, what I did was to generated the ratio of Delta, based on 2TB's confirmed # of Cylinder(1915210):
Published 2TB usable: 1882.7GB
Actual usable: 1753.4GB (=1915210/1024/1024/1024*512*128*15)
Ratio: published/actual = 1882.7/1753.4 => 1.073726.
I used this ratio to calculate actual usable are 536.73GB/91.644GB, for 600GB/100GB drive respectively.
Based on this actual sizing, with the previous formula "Cylinders = GB / 15 / 128 / 512 * 1024 * 1024 * 1024". I had the following cylinder number, respectively:
586251 - 600GB Drive
100099 - 100GB Drive.
It'd be nice to confirm the above with the ""symdisk list -cyl" command output. Anyway, the layout based on these sent out to EMC for validation. We shall see.
AranH1
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October 25th, 2013 08:00
The formulas for converting GB to GiB using the formatted capacities from the EMC spec sheets work. I have confirmed it using the Cylinder count from EMC tools for each drive size. Listed below are the drive sizes with the Cylinder count from EMC tools, the formatted capacities in GB from the spec sheet, and the usable capacity in GiB which was calculated from the formatted capacity in GB.
Size
Systems
Systems
Anonymous
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February 6th, 2017 19:00
Do you happen to have the newest vmax3 drive specs?
Cibin Varghese
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February 14th, 2023 04:00
Size of one Block..................: 512 Bytes
Number of Blocks per Track.........: 128( DMX-3/4,VMax) 256(VMax-3/PowerMax)
Number of Tracks per Cylinder......: 15
One Cylinder - DMX,VMax............: 15 Tracks x 128 blocks of 512 bytes = 960KB
One Cylinder - VMax-3/PowerMax.....: 15 Tracks x 256 blocks of 512 bytes = 1920KB
DMX,VMAX
GB = Cylinders * 15 * 128 * 512 / 1024 / 1024 / 1024
Cylinders = GB / 15 / 128 / 512 * 1024 * 1024 * 1024
VMAX-3/PowerMax
GB = Cylinders * 15 * 256 * 512 / 1024 / 1024 / 1024
Cylinders = GB / 15 / 256 / 512 * 1024 * 1024 * 1024