Fibre Channel disk subsystem
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Symmetrix DMX-3 Hardware
is presented to the target host by the DMX-4 or DMX-3. If the device
is re-labeled, there may be potential issues with data availability.
This is because Solaris reserves two cylinders from every device for
use by the operating system. DMX-4 and DMX-3 cylinders are twice
as large as cylinders from previous generation Symmetrix disk
arrays, meaning that the operating system will overwrite the last 1920
sectors of the user data area with an area reserved for operating
system use. It should be noted that, regardless of a difference in
geometry between the label and the actual disk, no issue will be seen
if the disk is not re-labeled by the user. This potential issue has been
resolved with the introduction of Flexible Device Geometry.
To alleviate any potential for corruption, two features have been
added to Symmetrix Enginuity. A bin file setting has been included
that allows the DMX-3 and DMX-4 to present an external device
geometry for all Symmetrix devices that is identical to the device
geometry of earlier Symmetrix arrays. Functionality has also been
added to Enginuity that allows alternate disk geometry to be
presented on a device by device basis.
Note: Contact your EMC Customer Engineer to determine if this feature
should be enabled on your Symmetrix DMX system.
IBM CKD DASD disk
emulation
The Symmetrix DMX system appears to mainframe operating
systems as a 3990-6, 2105, or 2107 controller. The physical disk drives
can appear to the mainframe operating system as a mix of multiple
3390 and 3380 device types. All standard models of the 3380 or 3390
volumes can be emulated up to the physical volume sizes installed.
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