Fixed-sized VHD vs Dynamically Expanding VHD - what is the performance penalty?
i running hyper-v r2 server dual-cpu, each cpu being quad-core, lots of ram , several mirrored arrays of sas drives. for key vm guests (the ones need performance), dedicating raid1 array vhd.
i have been of understanding dynamically-expanding disks have performance penalty associated them compared fixed-sized vhd.
what performance penalty if use dynamically-expanding vhd instead of fixed-size vhd logical size of vhd same?
and if put 1 guest's vhd onto own disk (raid1 array), diminish or mitigate performance penalty?
would if periodically defragmented dynamically-expanding vhd?
here specific situation , reason ask:
i need guarantee performance particular win 2003 std vm. it needs have 100gb of disk space. i have given fixed-sized 100gb vhd on own raid1 array of 146gb sas drives. performance fine.
what not make backup of vhd, being full 100gb in size, takes 45 minutes send server on gigabit network connection. the size of data within vhd 25gb. in other words, if disk dynamically expanding, backup might take 10 minutes.
i don't copy often. in fact, use ntbackup within guest vm regular weekly backups , of course, backups data , 25gb , isn't bad @ all.
but tonight, i'm going firmware upgrade on raid controller , i'm thinking right thing backup entire vm host. and process, entire 100gb of vm guest needs copied. if guest..and matter, other vms, using dynamically-expanding vhds, big backup of should take possibly less time. but i'm concerned possible performance hit.
looking advice on matter. thanks.
hi,
you can check following blogs.
hyper- v dynamic expanding or fixed size vhd?
http://blogs.technet.com/mghazai/archive/2009/09/04/hyper-v-dynamic-expanding-or-fixed-size-vhd.aspx
hyper-v , vhd performance - dynamic vs. fixed
hyper-v virtual hard disk (vhd) performance white paper
vincent hu
Windows Server > Hyper-V
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