Just my 2 cents: I've shrinked lots of LUNs in the past and never had issues with data corruption or anything like that; client OS was a broad range from Windows 2008R2 to Windows 2012R2, IBM AIX, Debian Linux and one Solaris system. You just need to make sure to shrink the filesystem first and free up space at the end of the LUN. I do usually shrink the filesystem to a level below of what I really want to shrink it, f.ex. if I want to shrink the LUN from 7TB to 3TB, I would shrink the FS to 2.9TB and will then shrink the LUN to 3TB and increase the FS afterwards again to fill up the free space at the end of the LUN just because I'm a coward and don't trust the differnt interpretations of what a Gigabyte is worth. If you chop of one Megabyte too much, your filesystem will be in a bad state, so better to be safe than sorry.
One thing you have to take care about is LUN geometry though, a given LUN cannot be increased larger than 10 times the initial size, so f.ex. if you create a LUN with 100GB, it cannot be made larger than 1000GB which also applies to LUN shrinks (or truncates) then.
Best,
Alexander Griesser Head of Systems Operations
ANEXIA Internetdienstleistungs GmbH
E-Mail: AGriesser@anexia-it.com Web: http://www.anexia-it.com
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-----Ursprüngliche Nachricht----- Von: toasters-bounces@teaparty.net [mailto:toasters-bounces@teaparty.net] Im Auftrag von Martin Gesendet: Dienstag, 5. Januar 2016 08:48 An: toasters@teaparty.net Betreff: Re: SnapDrive shrink lun
All the methods I've seen of shrinking a LUN have the caveat of taking a backup first. I came to the conclusion that if you have to take a backup of the LUN why not just do as others have said and create a new LUN and copy the data over. It does mean you need the free space to create the additional LUN but if unless you skip taking a backup (obviously not a good idea) you're going to need space somewhere.
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