How many data is written?

Hi all,

I'm struggling with calculating a RAID5 set on a symmetrix.

EMC has deployed our Symmetrix with hypers of the kind RAID5 (7datadisks + 1paritydisk ).

I'm trying figure out how many data is written on each of the data disks in this RAID5 set.

This is what I can come up with at the moment:

Partial Output of symdev command:

Device Block Size 512B

Device Capacity
       {
       Cylinders            :      14788
       Tracks               :     221820
       512-byte Blocks      :   28392960
       MegaBytes            :      13864
       KiloBytes            :   14196480
       }

Geometry             : Native
        {
        Sectors/Track        :        128
        Tracks/Cylinder      :         15
        Cylinders            :      14788
        512-byte Blocks      :   28392960
        MegaBytes            :      13864
        KiloBytes            :   14196480
        }

RAID-5 Device Information
       {
       Number of Tracks in a Stripe                : 4
       Overall Ready State of RAID-5 Device        : Ready
       Overall WriteProtect State of RAID-5 Device : Enabled
       Member Number of the Failing Device         : None
       Member Number that Invoked the Spare        : None
       Disk Director (DA) that Owns the Spare      : None
       Copy Direction                              : N/A
       RAID-5 Hyper Devices (7+1):
           {
           Device : 10BD
               {
               --------------------------------------------------------------
                Disk     DA       Hyper       Member    Spare       Disk
               DA :IT   Vol#   Num Cap(MB)  Num Status  Status  Grp#  Cap(MB)
               --------------------------------------------------------------
               12B:D1    903    47    1984    1 RW      N/A        3   286102
               05D:C1     47    47    1984    2 RW      N/A        3   286102
               05A:D1   1116    47    1984    3 RW      N/A        3   286102
               12C:C1     47    47    1984    4 RW      N/A        3   286102
               05B:C1     47    47    1984    5 RW      N/A        3   286102
               12D:D1   1042    47    1984    6 RW      N/A        3   286102
               12A:C1     47    47    1984    7 RW      N/A        3   286102
               05C:D1   1042    47    1984    8 RW      N/A        3   286102
               }

If my calculations are correct the Track size is 64kB. With a stripe size of 4 tracks, I get a 256kB stripe size that is written over 7 data disks.

The data that is written to each member of the data disks would be 36.57kB. I find this a very odd number.

Can someone verify the calculation?? Please!

Message was edited by: mamer [added 'tracks' to clarify calculation]