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2815
GetDisk LUN size
Hello,
I am using the VILT to study for my VNX TA. I am currently studying for VNX Storage Solutions Design.
I was reviewing one of the labs and the question was:
Q: If disk 1,0,0 is part of a 4+2 R6 group, what is the total user size of the LUNs on the RAID Group? How much space is occupied by the LUNs on the RAID Group?
A: User size is 341.333333 x 6 = 2,048 GiB. The LUNs occupy 3,072 GiB on disk.
The getdisk output is:
===================================================================
Bus 1 Enclosure 0 Disk 0
Vendor Id: SEAGATE
Product Id: ST320004CLAR2000
Product Revision: BS17
Lun: 400 401 402 403
Type: 400: RAID6 401: RAID6 402: RAID6 403: RAID6
State: Enabled
Hot Spare: 400: NO 401: NO 402: NO 403: NO
Prct Rebuilt: 400: 100 401: 100 402: 100 403: 100
Prct Bound: 400: 100 401: 100 402: 100 403: 100
Serial Number: 9WM6CYBA
Sectors: 715827882 (349525)
Capacity: 1878379
Private: 400: 65536 401: 1073840128 402: 2147614720 403: 3221389312
Bind Signature: 0xb81c5, 0, 0
Hard Read Errors: 0
Hard Write Errors: 0
Soft Read Errors: 0
Soft Write Errors: 0
Read Retries: N/A
Write Retries: N/A
Remapped Sectors: N/A
Number of Reads: 4704282
Number of Writes: 0
Number of Luns: 4
Raid Group ID: 3
Clariion Part Number: DG118032750
Request Service Time: N/A
Read Requests: 4704282
Write Requests: 0
Kbytes Read: 301074048
Kbytes Written: 0
Stripe Boundary Crossing: 0
Drive Type: NL SAS
Clariion TLA Part Number:005049277PWR
User Capacity: 341.333333
Idle Ticks: 4494147
Busy Ticks: 22171
Current Speed: 6Gbps
Maximum Speed: 6Gbps
===================================================================
Can someone help me with how did the calculations was done?
Thanks in advannce.
Richard_Butler
84 Posts
1
May 1st, 2012 14:00
Hello SaramiR,
(I'm not familiar with this VILT specifically, but are you saying that this is the answer that is given to you in the VILT?)
Anyway, if the RAID group is R6(4+2), then we have 4 disks worth of user-capacity (striped) and 2 disks worth of protection-capacity.
=> [(user-capacity + protection-capacity)/user-capacity] = [4+2]/4 = 6/4 = 3/2.
=> 2048 x 3/2 = 3072.
Does that help?
Rgds, Richard.
SaramiR
7 Posts
0
May 2nd, 2012 00:00
Thank you. That makes perfect sense.