emc的DMX和VMX的VOLUME size的解释

Volume Size

When creating device, the size of the device needed in number of cylinders. In Symmetrix DMX/Vmax models(Enginuity 5671 and earlier), a cylinder of an FBA device contains 1920 512-byte blocks, or 0.98 megabytes. In earlier Symmetrix models, a cylinder of an FBA device contains 960 512-byte blocks or, 0.468 megabytes.

- Enginuity 5671 and earlier: 960 512-byte blocks
- Enginuity 5771+: 1920 512-byte blocks

For DMX/VMAX(Enginuity 5771+):

1 Sector = 16* 512 byte Block = 8KB
1 Track(RW Head) = 8* Sectors = 8*8=64KB
1 Cylinders = 15*Tracks = 15*64KB = 960KB

So for example:

9000 Cylinder Device = 9000*15*8*16*512=8,847,360,000=8.8GB

The Maximum Volume size that can be configured on a VMAX is 262668 cylinders. If host applications require larger volumes, multiple volumes can be combined to form a metavolume.

Maximum Configurable Volume = 262668 Cylinders = 245760 MB = 240GB

For Enginuity 5771+: 1920 512-byte blocks

To convert a device size in blocks to cylinders for Enginuity 5671 and earlier, use the following:

cylinders = (number of blocks) / 960

To convert a size in megabytes to cylinders, use the following for Enginuity 5671 and earlier:

cylinders = (devicesize in megabytes) x 10242 ÷ (960 x 512 bytes)
= megabytes * 1048576 / (512 * 960)
= (size in megabytes) x 2.133

Devices that are going to be used as BCV, RDF, or metamembers need to precisely match the corresponding devices in size. Use the symdev/sympd show command or the symdev/sympd list -cyl command to see relevant device sizes.

Volume Configuration

On older Symmetrix arrays the maximum numbers of hyper volumes permitted on a disk was a user settable parameter.
- With 5874, this number is fixed at 512.
- With 5875 the number is 1024.
It's recommended by EMC to use fewer and larger Hypers, because there is less contention for the resources on the physical disk.