Cannot start VM insufficient memory when there is enough.

hi,

i've seen above error 2008r2 servers , hoped fixed in server 2012 had again today on small test machine.

if allocate memory vm fits physical ram of host following error:

cannot start vm cannot allocate sufficient memory or something.

my test machine has 16gb ram if create 2 vms each 7gb ram 1 won't start above error.

if reboot host can start them.

this leads me believe disk ram caching of windows tripping memory allocation. because after reboot cache gets cleared , can start them.

any idea if can disable filecaching? don't need on vm host.

kind regards,

kor

i can confirm behavior well.

before upgraded server 2008r2 server 2012, able run of hyper-v machines @ same time, , reboot 1 whenever needed to.

however, after installed server 2012 (i went storage server 2012 hyperv test environment since has both file server role , hyper v available), noticed unable start same amount of vm's (i imported vm's 2008r2 environment), received message system not allocate enough system resources (ram in particular), though task manager/resource manager states 50% of ram still unused/available (i have total of 16gb on host).

in server 2008r2 used rdp host , manage way, , run other applications in user account; , exit rdp session (not logging off) when done. did same in server 2012, , that's when started notice after reached 50% ram usage, no longer start vm's (i didn't import them @ once, 1 one when needed them didn't notice right away after moving 2012). there's total of 4 applications installed on server these ones need on host itself, kept pretty clean , pretty sure wasn't software issue.

also rebooting server didn't help, since moment logged in, receive same messages cannot allocate anymore resources vm start. after logging off, , connecting hyper-v host using hyper-v manager in windows 8, have no problems starting these additional vm's , machines using dynamic memory able receive additional ram again well.

i planned on using server in "core" mode (so removing shell , support applications/management tools displayed) choose run in full gui mode during initial configuration. after running issue wasn't sure issue was, put off. however, knowing user session somehow "claims" (or doesn't release?) more memory shows (taskmgr said session used 300mb), motivates me more run box server2012-core os , not log onto locally anymore/through rdp , remote management tools / manage server.

sorry long post, wanted share experiences on issue after moving hyper-v 3.0.

kind regards,

stephan schwarz

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