vSphere Storage Appliance

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  • 1.  Thin Provisioning worse off?

    Posted Sep 24, 2010 07:53 AM

    Thin provisioning, which suppose to reduce storage, actually demand even more storage faster! Here's why:

    Said a VM is given 80GB and used only 10GB for now. The projection of 10GB growth per year mean that 80GB will be insufficient 8 years later. However, the daily temp file of 50GB will mean that there will be insufficient storage for the temp file just 3 years later.

    To overcome this, a 100GB SAN storage is presented as a 2TB volume to this VM so that additional storage can be purchase 3-5 years later easily. However, due to the way OS handle file deletion, 100GB will be insufficient immediately just after 2 days instead of 3 years!

    btw, how do we free up the storage after running sdelete on Windows without having access to storage vMotion? The shrink function in the vmtools does not work.



  • 2.  RE: Thin Provisioning worse off?

    Posted Sep 24, 2010 08:20 AM

    However, due to the way OS handle file deletion, 100GB will be insufficient immediately just after 2 days instead of 3 years!

    Deleting the files enlarges the disk? You created a snapshot on that maschine?

    Regards



  • 3.  RE: Thin Provisioning worse off?

    Posted Sep 24, 2010 09:17 AM

    No, deleting the file simply does not free up the storage for new files to store into. And when 100GB is used up, there will be a write delay error if Windows doesn't crash.

    btw, no snapshot.



  • 4.  RE: Thin Provisioning worse off?

    Posted Sep 24, 2010 09:13 AM

    Said a VM is given 80GB and used only 10GB for now. The projection of 10GB growth per year mean that 80GB will be insufficient 8 years later.

    Yes, 8 years later. But you have options. Assign 160 GB thin in the beginning so it will last 16 years. You doubled the amount of time you do not have to do anything regarding this disk. If 16 years are gone and you're still using vSphere 4.x, you can still expand the virtual disk size.

    However, the daily temp file of 50GB will mean that there will be insufficient storage for the temp file just 3 years later.

    Which temp file? A file in the guest? If there's a daily temp file of 50 GB created within the guest, you might have to recalculate your disk sizes. If there is the need to store 50 GB each day, even temporarily, you need need 50 GB storage. With every system, every product everywhere in the world (except backend mechanisms like de-duplication, etc).

    To overcome this, a 100GB SAN storage is presented as a 2TB volume to this VM so that additional storage can be purchase 3-5 years later easily. However, due to the way OS handle file deletion, 100GB will be insufficient immediately just after 2 days instead of 3 years!

    btw, how do we free up the storage after running sdelete on Windows without having access to storage vMotion? The shrink function in the vmtools does not work.

    Yes, that is known and works as designed. The fact that someone does not have access to sVMotion makes thin provisioning and sVMotion not a bad function, as it still helps all other people which have access to that.

    We do not have the Enterprise+ license, so we do not have all the nice things, but I still like them, even if I can't use them.


    AWo

    VCP 3 & 4

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  • 5.  RE: Thin Provisioning worse off?

    Posted Sep 24, 2010 09:19 AM

    AWo, read this for actual situation: http://communities.vmware.com/message/1616471#1616471



  • 6.  RE: Thin Provisioning worse off?

    Posted Sep 24, 2010 09:21 AM

    So what?


    AWo

    VCP 3 & 4

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  • 7.  RE: Thin Provisioning worse off?

    Posted Oct 13, 2010 09:55 AM

    It means I won't be able to free up or reuse the unused storage unless I find a way to zero-fill the free space in the VMFS volume that is thin provisioning from a SAN storage.

    Check this out: http://communities.vmware.com/thread/288556



  • 8.  RE: Thin Provisioning worse off?

    Posted Oct 14, 2010 08:08 AM

    You must differentiate:

    If you want to free up space on the VMFS volume you need to zero-out the space in the guest to shrink the virtual disk. That is something related to VMWare.

    If you have a thin provisioned SAN volume and you need to zero-out the space there, as well, that is related to the SAN box.

    But as you see, it seem to be a general technical issue as depending on the level you look at, zeroing-out the free space seems to be a requirement.

    We use thin provisioning on the virtual disk level and it pays off. Why? In most of the cases the virtual disks tend to grow or the size doesn't change much. Disks which grow doesn't need to be shrinked, disks which do not grow, as well. If there is a case where much space needs to be released we can run it during maintenance times.

    Thereby thin provisioning gives us the benefit of moving guest more quickly with svMotion and to save space to hold more guests.

    Regarding thin provisioning on the SAN layer I do not see the benefit in our case, as I do not want any space allocated to VMware to be taken away from it, as the usage by VMware also tends to grow, not to shrink.

    Even if there are greater changes on a regular basis, like deploying many servers and decomissioning them again, which uses a lot of space shortly, you will need the space again and again. If that was only a one-time thing, you can free it up during maintenance again.


    AWo

    VCP 3 & 4

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