Semester7

Notes of courses done/attended in semester 7 in college

dynamic resource mgmt in cloud
dynamic assignment nahi kia toh nuksaan, cloud lene ka fayda nahi
users use differently
dynamic monitoring system is reqd, user ko chahiye ya nahi
when it is identified, then usko do to fulfill SLO, agar us system pe resource na ho, toh shift the vm

load balancing
- move vms to less busy host
- make use of newly added capacity
- vm consolidation
maintenance
- move vms off a host b4 it is shut down
recovery from hsot failure
- restart vm on diff host
challenges are involved
- when u r moving, service might be running, so end user ko allow to use service while migrating
- say, migration ke middle me tha, host a se b pe le ja raha
- a cannot clear up resources until transfer is complete
- challenges with n/wing
  - ip addresses etc would change when move vm
  - tcp connection break

cold migration
- completely shutdown on first system
- restart on host 2
warm
- suspend vm on host 1
- pause kia, shutdown nahi
- copy ram and cpu registers associated with this vm on system and paste in other
live
- vm is not stopped
- bahut chote time ms me ke lie it is
- copy across ram while vm continues to run
- keep transfering pages
- when u suspend vm, what is not transferred is very less

downtime
- suspension start time, service nahi available
- perceived by end user
- period during which service is unavialbale due to no running instance of vm
total migration time
- migration init operation se resource cleanup on host 1 time
minimize both
wrt downtime reln b/w cold, warm, live migration, and wrt total migration time
- downtime
  - L < W < C
- total
  - L > W > C
  - cold me minimum, bcz shutdown kardia, resources not held
  - warm me resources are held
  - live me bahut n/w calls

1st round me m/r time lega
we can compute page dirtying rate (#pages dirtty per second)
d/r < 1 => converge kar jayega
else, won’t, time will keep increasing
if d/r >= 1
- hot pages dekh (stack local variables wale etc)
  - those keep changing very frequently
- do not transfer those
- keep those for last round
problem

subnet hote n/w me
prefix common to all in subnet
system moves from one subnet to other, it has to be added to vm or configured somewhere
VLANs the
- physical locn does not define subnet
- configurations define subnet
this config has to be enabled agar diff n/w me ja ra
agar same n/w me ja ra, toh koi bt nahi, prefix same hai
same ip chahiye toh config me dalna hoga

migrating storage
- wan = closed nahi
- vm moves like sun movement around earth
- india me sun => vm close to datacenter in india
- this is wan migration
- here, shared storage is not possible, latency and all
  - lans me easy
- storage rpelication karle
  - move storage ahead of vm
- or, on demand fetch
  - copy file when needed
n/w reconfiguration
- layer 3, layer 2 Virtual private Networks use karle
- ip address change on movement
- so, kuch proxy ya reconfiguration is required
- so that new connections come to this machine only but existing are forwarded here from prev one
Use cases
- compute infra around the world
- maintenance and upgrades of a site
- collaborative projects
- cloud burst scenarios