Deduplication and Deletion Support

Medium · Sun Sep 16, 2012 6:16 pm

Hey Guys

I have been playing around with the free version of Starwinds ISCSI software V6.

I have made a dedup-image on a hardware raid 10 system. I have ticked the Deletion Support (which i know is experimental)

I have moved all my VMs away from the dedup-image and on to a dedicated NAS box (temporary ofcourse)

But i noticed that the dedup-image is actually bigger than before i started to move the VMs away, to me it seems like its not doing its job about "cleaning up" afterwards, shouldnt it be less GB?, since I have nothing on the image anymore.

Best Regards

Michael

Sun Sep 16, 2012 8:08 pm

"Delete" and "free space re-claim" are not the same things. With V6 StarWind does delete the data it has no references to but it
does not give back used space to NTFS. With V6 successor we'll release first beta real soon you'll see your actual container image
actually shrinking after you'd delete the data (unused space re-claim + unmap + zero patter write). So stay tuned

Medium wrote:Hey Guys

I have been playing around with the free version of Starwinds ISCSI software V6.

I have made a dedup-image on a hardware raid 10 system. I have ticked the Deletion Support (which i know is experimental)

I have moved all my VMs away from the dedup-image and on to a dedicated NAS box (temporary ofcourse) But i noticed that the dedup-image is actually bigger than before i started to move the VMs away, to me it seems like its not doing its job about "cleaning up" afterwards, shouldnt it be less GB?, since I have nothing on the image anymore.

Best Regards

Michael

Medium · Wed Sep 19, 2012 6:51 pm

Hey Anton

Thanks for the fast answer, I will for sure be looking forward to test out the next release

Best Regards

Michael

Fri Sep 21, 2012 3:14 pm

By the way, I`d like you to know that you are always welcomed to participate for our Beta-Testing program, You can register it by using the link below:
http://www.starwindsoftware.com/beta-testing-program

Medium · Tue Oct 02, 2012 6:12 pm

Well probably i should have made a new forum post, but here we go...

I have noticed that with the Starwind version 6.0.4768, when i remove and re-add a dedup-device, the memory is not consumed as it was the first time i added a device with cache(ram). I have been looking with taskman on a Windows Server 2008 R2, I get the memory back when i remove the device the first time as I would expect, but it wont consume the memory the next time i re-add the device, not always.

It is correct that when i set 22GB of cache it should eat 22GB of ram from the host?.

Tue Oct 02, 2012 8:11 pm

Right, this post does not belong to this thread... OK, dedupe devices consume memory in two ways:

1) Hash tables. 6 bytes / hash block. ~2GB / 1TB of served capacity.

2) Cache. As much as you'd allocate. YES, if you had set 22GB then it will take UP to 22GB of memory.

Medium wrote:Well probably i should have made a new forum post, but here we go...

I have noticed that with the Starwind version 6.0.4768, when i remove and re-add a dedup-device, the memory is not consumed as it was the first time i added a device with cache(ram). I have been looking with taskman on a Windows Server 2008 R2, I get the memory back when i remove the device the first time as I would expect, but it wont consume the memory the next time i re-add the device, not always.

It is correct that when i set 22GB of cache it should eat 22GB of ram from the host?.

Medium · Thu Oct 04, 2012 4:25 pm

Hey Anton

My point was that I noticed that when i set the cache on the dedup-device ex. 22GB It didnt consume the memory from the Host, is that something you guys have seen before?

If i remove the device again, and add it again then it would consume the 22GB of memory of the host, maybe it was bug or something in the latest release of Starwind V6, thou its not always it does that.

best regards

Michael

Sat Oct 06, 2012 3:25 pm

StarWind is not always using whole RAM if it was assigned to cache, i.e. if host OS will require to use some of the RAM that is used for StarWind cache, our engine will easily give away required ammount of RAM. Also RAM may start to be reserved not initially - have you tried to wait for a while (probably this is silly question but still)?