IBM Support

DS8870 Potential Long I/O Response Time with VMWare XCOPY command

Flash (Alert)


Use of the Hardware Accelerated Move VAAI function (XCOPY) to perform multiple clone operations in parallel may cause long IO response times for unrelated IO.


If the Hardware Accelerated Move VAAI (XCOPY) function of VMware® ESX/ESXi 5.0 or higher is used to perform multiple clones (five or more) in parallel to the same DS8870, on firmware levels less than bundle (, it may trigger a condition where response times for other read/write IO to the same DS8870 will increase disproportionately.  This condition will persist until the clone operations complete.
Note: Clients with DS8870s using the XCOPY function and on microcode below bundle are exposed to a potential loss of access issue if the source and target volumes reside on different clusters (i.e. the copy is a cross cluster copy).


Until the firmware on the DS8870 can be updated to fix level, this problem can be averted by limiting the number of clones being done in parallel to four or fewer. Alternatively, the XCOPY function may be disabled on any attached VMware® hosts using the following instructions. The parameter to be disabled is the "HardwareAcceleratedMove".


The fix to this issue is now available in DS8870 bundle Clients with DS8870s using the XCOPY command should arrange with IBM Service to update their firmware to a bundle with the fix at their earliest convenience.

Document information

More support for: DS8870

Version: 5.0

Operating system(s): VMware

Software edition: N/A

Reference #: S1004351

Modified date: 29 April 2014

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