{"id":9490,"date":"2009-03-04T10:39:00","date_gmt":"1999-11-29T20:00:00","guid":{"rendered":"https:\/\/aidanfinn.com\/?p=9490"},"modified":"2009-03-04T10:39:00","modified_gmt":"1999-11-29T20:00:00","slug":"do-not-use-dynamic-disks-in-production","status":"publish","type":"post","link":"https:\/\/aidanfinn.com\/?p=9490","title":{"rendered":"Do Not Use Dynamic Disks In Production"},"content":{"rendered":"

Microsoft has been quite clear about this.\u00a0 Dynamic and Differential Disks<\/a> are not supported in production.\u00a0 There is a serious performance hit when you move away from Pass through or Fixed disks.\u00a0 This means that things like snapshots are not supported in production.\u00a0 Snapshots use differential disks.\u00a0 There\u2019s another catch: if a serious amount of time has passed since the snapshot then the differential disk will grow substantially and a merge might take a very long time to process.<\/em> <\/p>\n

We have one lightweight box that I P2V\u2019d a while back using VMM 2008.\u00a0 When I did the conversion the target host I used was my lab server.\u00a0 It has a minimal amount of storage so I used dynamic VHD\u2019s.\u00a0 I\u2019ve since moved the VM onto our production cluster and upgraded the VM OS from W2003 to W2008.\u00a0 It does some very lightweight management work but once a month the amount of data on it bursts.\u00a0 I decided to leave the disks as VHD for a while \u2013 mainly because I\u2019ve been snowed under with higher priority technical work for clients and supporting our sales\/marketing efforts. <\/p>\n

A few weeks ago we had a series of disk performance alerts from OpsMgr for the VM in question.\u00a0 It was performing below par.\u00a0 That was before the OS upgrade.\u00a0 Last night, it had a series of alerts again.\u00a0 Is it a disk subsystem fault?\u00a0 Nope \u2013 It\u2019s an EVA SAN with fibre channel.\u00a0 The other VM\u2019s on the host are being actively pushed while the alerting VM is barely hitting host resources at all.\u00a0 <\/p>\n

The issue is pretty simple: the dynamic disk is having to expand when new data comes along and this slows down the process.\u00a0 This is clear supporting evidence for Microsoft\u2019s recommendation. <\/p>\n

DO NOT USE DYNAMIC DISKS IN PRODUCTION! <\/p>\n

I know, it can save you on disk space.\u00a0 But is that really worth it when you have production systems and performance is important?\u00a0 It\u2019s like RAM oversubscription on other virtualisation platforms.\u00a0 In theory it\u2019s great.\u00a0 When managed properly it\u2019s a money saver and performance isn\u2019t hit.\u00a0 But when it\u2019s not managed correctly then you take a huge hit and performance\/availability issues arise, e.g. I heard of one hosting company in Ireland that likes to \u201cburst\u201d memory\/RAM and they\u2019re having major issues with customer VM uptime\/performance issues. <\/p>\n

Performance = vendor support = better availability = happy customers\/users = your job is a little safer. <\/p>\n

That\u2019s enough blogging for now.\u00a0 I\u2019ve some dynamic disks to convert<\/a>. <\/p>\n","protected":false},"excerpt":{"rendered":"

Microsoft has been quite clear about this.\u00a0 Dynamic and Differential Disks are not supported in production.\u00a0 There is a serious performance hit when you move away from Pass through or Fixed disks.\u00a0 This means that things like snapshots are not supported in production.\u00a0 Snapshots use differential disks.\u00a0 There\u2019s another catch: if a serious amount of … Continue reading “Do Not Use Dynamic Disks In Production”<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"om_disable_all_campaigns":false,"_monsterinsights_skip_tracking":false,"_uf_show_specific_survey":0,"_uf_disable_surveys":false,"_wpcom_ai_launchpad_first_post":false,"footnotes":""},"categories":[20],"tags":[],"class_list":["post-9490","post","type-post","status-publish","format-standard","hentry","category-hyper-v"],"aioseo_notices":[],"aioseo_head":"\n\t\t\n\t\n\t\n\t\n\t\n\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t