Stan Hoeppner schrieb: > On 3/28/2013 8:21 AM, Jan Perci wrote: > > > Normally I would use raw mappings and XFS directly on the volumes. But > > there is a hard requirement to support VM snapshots, so all the data must > > reside within VMDK files on the VMFS datastores. > > Since when? ESX has had LUN snapshot capability back to 3.0, 6 years or > so. It may have required the VCB add on back then. Snapshots are possible with RDM in virtual compatibily mode, not physical mode (> 2 TB). http://pubs.vmware.com/vsphere-51/topic/com.vmware.vsphere.storage.doc/GUID-0114693D-94BF-4D0E-9BA4-416D4A51A5A1.html > Is this simply a limitation of the freebie version? If so, pony up and > pay for what you need, or switch to a FOSS solution which has no such > limitations. No, thats the limit for all versions. > VMFS volumes are not intended for high performance IO. Unless things > have changed recently, VMware has always recommended housing only OS > images and the like in VMDKs, not user data. They've always recommended > using RDMs for everything else. IIRC VMDKs have a huge block (sector) > size, something like 1MB. That's going to make XFS alignment difficult, > if not impossible. I can't remember that I've every found this recommendation on a vmware page. http://blogs.vmware.com/vsphere/2013/01/vsphere-5-1-vmdk-versus-rdm.html > I cannot stress emphatically enough that you should not stitch 2TB VMDKs > together and use them in the manner you described. This is a recipe for > disaster. Find another solution. I'm seeing more and more requests for VMs with large disks lately in my env. Right now the max. is ~2 TB. I'm also thinking about where to go, > 2 TB ist only possible with pRDMs which can't be snapshotted. You have to use the snapshot features of your storage array. Ralf _______________________________________________ xfs mailing list xfs@xxxxxxxxxxx http://oss.sgi.com/mailman/listinfo/xfs
