We have noticed that a cluster we upgraded to 1.1.6 (from 1.0.*) still has a single large (~4GB) row in system.Migrations on each cluster node.  We are also seeing heap pressure / Full GC issues when we do schema updates to this cluster.  If the two are related, is it possible to somehow remove/truncate the system.Migrations CF?  If I understand correctly, version 1.1 no longer uses this CF, instead using the system.schema_* CF's.   We have multiple clusters and clusters which were built from scratch at version 1.1 or 1.2 do no have data in system.Migrations.

I would appreciate any advice and I can provide more details if needed.  

-Andrew

Andrew Cooper
National Information Solutions Cooperative
3201 Nygren Drive NW
Mandan, ND 58554
e-mail: andrew.cooper@nisc.coop
phone: 866.999.6472 ext 6824
direct: 701-667-6824