tag:blogger.com,1999:blog-27348612.post8247690946794834263..comments2020-03-14T02:48:28.979-05:00Comments on Storage: SnapDrive for Windows 5.0 - Thin Provisioning and Space ReclamationNick Triantoshttp://www.blogger.com/profile/09961325835631522741noreply@blogger.comBlogger6125tag:blogger.com,1999:blog-27348612.post-42256886758308042822007-07-10T18:37:00.000-05:002007-07-10T18:37:00.000-05:00Correct on all counts.Indeed, Longhorn is suppose ...Correct on all counts.<BR/><BR/>Indeed, Longhorn is suppose to provide the ability to shrink. I believe HP recently announced the ability to shrink LUNs but that won't be available until the MS Longhorn release but given the cautious nature of enterprises and how long the upgrade cycle takes, I suspect there's still be a whole bunch of 2003 servers around in the next 2-3 yrs. <BR/><BR/>I think the space reclaim ability is a nice feature to have and it maybe provide a benefit, depending on the I/O characteristics of the application.Nick Triantoshttps://www.blogger.com/profile/09961325835631522741noreply@blogger.comtag:blogger.com,1999:blog-27348612.post-10574322774002211862007-07-10T18:12:00.000-05:002007-07-10T18:12:00.000-05:00wow that was fast...I see what you are saying, blo...wow that was fast...<BR/><BR/>I see what you are saying, blocks allocated in the filesystem will be touched more often in this scenario because ntfs tends to use previously untouched blocks. But it would never use more than the maximum capacity of course.<BR/><BR/>It also sounds like you are saying if a block is erased (filled with zeros, or a recognized erase pattern) these thin provisioning arrays have some facility to reclaim the block? That would be the only way the array could shrink a thin provisioned LUN that had been previously filled, without host filesystem assistance (i.e. the host telling the array it's no longer using the block. Apparently the windows server 2008 has a protocol to do something like this, for what it's worth.).<BR/><BR/>Most filesystems don't erase freed blocks by default, it's pretty expensive to do this.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-27348612.post-67399455629607337162007-07-10T18:08:00.000-05:002007-07-10T18:08:00.000-05:00Correct. The Array does reclaim blocks and it will...Correct. The Array does reclaim blocks and it will revert the LUN back to "thin". <BR/><BR/>So we're working on other platforms/filesystems but I can't really provide any specifics given that it's NDA info and somebody is sure to slap my hand by providing this in a public forum. <BR/><BR/>I hope you understandNick Triantoshttps://www.blogger.com/profile/09961325835631522741noreply@blogger.comtag:blogger.com,1999:blog-27348612.post-28741623073821259872007-07-10T18:02:00.000-05:002007-07-10T18:02:00.000-05:00One more thing... It looks like the tool you are r...One more thing... It looks like the tool you are referring to will allow the array to reclaim blocks once they have been freed on the host, allowing the LUN to again revert to being 'thin'. <BR/><BR/>Will this tool be available for other host platforms? Tired of vendors always emphasizing/promoting billy.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-27348612.post-77810996536531027232007-07-10T17:56:00.000-05:002007-07-10T17:56:00.000-05:00Ok so here's a post from Searchstorage.com from a ...Ok so here's a post from Searchstorage.com from a user experiencing what I was talking about: <BR/><BR/>But other users haven't had such idyllic experiences. Nick Poolos, systems/network specialist at The Ohio State University's Fisher College of Business, saw the NTFS file systems mounted on a Compellent Storage Center SAN grow abnormally large when using the array's Dynamic Capacity feature. <BR/><BR/>"At issue, according to Bob Fine, Compellent's product marketing manager, is Microsoft's "undelete" feature, which just marks blocks to be released without actually erasing them. Rather than reusing released blocks, NTFS prefers new, unused blocks, which caused the thin-provisioned volume to swell to its maximum allocated size. Fine says doing a periodic disk defragmentation may be a workaround. He adds that most users will never witness this problem because most environments grow gradually and don't delete much data." <BR/><BR/>whole article can be found here:<BR/> <BR/>http://searchstorage.techtarget.com/originalContent/0,289142,sid5_gci1188117,00.htmlNick Triantoshttps://www.blogger.com/profile/09961325835631522741noreply@blogger.comtag:blogger.com,1999:blog-27348612.post-74273064216886085612007-07-10T17:49:00.000-05:002007-07-10T17:49:00.000-05:00The readers comment doesn't make sense to me. The ...The readers comment doesn't make sense to me. The filesystem will not attempt to use different blocks after files have been deleted from a full (and therefore fully allocated on the array) LUN. It will use the same blocks that have been freed up, which are the ones already allocated.<BR/><BR/>It's true that once filled up, the LUN is no longer 'thin', but it will not require more blocks that the maximum allocation. Am I missing something?<BR/><BR/>-billy bathgatesAnonymousnoreply@blogger.com