Just sharing my experience or both X25-E & X25-M on the IMS.
That "Dongle" is basically doing 2 things:
1.Making sure that the SSDs are being recognized as SAS device so that the redundancy of the storage controller would work
2.Providing a more consistent performance at the I/O level
However, you will not benefit much from using X25-E as the LSI controller is just too slow. We are still wondering why Intel didn't want to include IOP348 in the IMS. Even with IOP348 (We are trying it with Adpatec 5805Z), it is very tough to make X25-M running at its potential as IOP348 is not really designed to support SSDs.
I seriously urge Intel to replace that slow LSI storage controller with IOP348, this was the reason we decided not to buy the IMS but to stick to standalone multiple 2U servers with Open-E SAN.
Do your calculation and explore if you really need X25-E instead of X25-M...
We also have a MFSYS25 with four X25-M 80GB (1.G.) in RAID5 and AXXTM3SATA installed. They performed very well for almost a year ago (without AXXTM3SATA ) and with CMM firmware 3.0 and ESX 3.5 U3. I was able to migrate VM's to the SSD datastore without any problems. But when I upgraded the CMM to 4.0 all hell broke loose (please see http://communities.vmware.com/thread/244797;jsessionid=4478D9EB51364DF2D26819CB24FA696E?tstart=0).
Last week I upgraded CMM to 5.5 and now it seems to work with X25-M RAID5 and ESX 4 U1. But I need to make some more tests.
Are any of you running ESX on MFSYS25 together with X25-M?
Intel and VMWare would not investigate our issue because X25-M is not officially supported on MFSYS25, only the X25-E disk are