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Partition compression on hyper-v

Patrick Neuner
Regular Advisor

Partition compression on hyper-v

Recently I found out, that when placing our lefthand vhdx files to tape, the compression ratio is very high. Way higher than Lto-5 tells it's average. 

 

I might even understand, why compression works well, we have primary nodes, that only hold about 1,8 TB of data, but due the lack of thin provisioning uses more as twice of it. All this is replicated to our VSA with helding snapshots for 30 days. This already uses about 8 TB of data....

 

Dedup of Windows 2012 would be nice, but won't work with VHDX that are running. 

 

Now I wonder what happens, if I use a compressed partition, where the vhdx files reside, would this probably gain about 50 % of storage back, or would it kill our server. 

 

As I understand NTFS compression, it will only decompress portions that are accessed. 

But I also know, you shouldn't use big files, well 2 TB are big files and might not even be saved on compresses partitions. 

 

I wonder if anyone tried it, or knows, that it's not possible anyway. 

 

Speed isn't an very important thing here. (Lefthand hammers the HDD's anyway all the time without even replicating or deleting snapshots. Very annoying as I wonder is it constantly shifting data from a to b and back to a...  ) Not very important of course means, that snapshot consolidation need to work and stuff, but penalties are fine. 

 

Thanks

Patrick 

 

 

 

 

3 REPLIES
oikjn
Honored Contributor

Re: Partition compression on hyper-v

are you trying to backup your VSAs like you backup your other VMs?  

 

Unless you only have a single VSA, this sounds like a bad idea.

 

Not sure I follow the logic of your "lack of thin provisioning" reasoning for a high dedupe ratio on a backup.  

 

 

Are you thinking of compressing the partition that holds the vhd file that is provisioned as the storage for the VSA?  If so, that is a BAD idea because of the performance hit you will take on the file both during normal use and during dedupe activity.  

 

backup your VMs or other data directly and not by backing up an image of each VSA.

Patrick Neuner
Regular Advisor

Re: Partition compression on hyper-v

Hi,

Thanks for your response. 
No, our VSA just helds the remote snapshots of our Lefthand Nodes. So it  is just sometimes used to gain some older version of files as it holds 30 days of snapshots but nothing used in production. 

 

I just thought as VSA is just a space waster, that a compressed partition could help. I know performance would go down, but if its just like 10-20 %, that would be fine, 

 

Bringing the VHDX to tape is just an additional messure to have something offline too, and there i noticed the high compression ratio. It's just kind of ridiculous that a from 1.8 TB of data we need 10 TB of space with 30 days worth of snapshots,  You are right, using any other backup solution and drop VSA completly would help and cut space usage by over 50 % and more. But the setup was way easier this way as we had the licence included.

Our contract will run out in less than 12 months, until then, we don't want to make big changes, we will just add storage to our VSA. 

Next year we have to think again anyways as we won't invest any dime into any lefthand solution. 

 

Thanks

Patrick

oikjn
Honored Contributor

Re: Partition compression on hyper-v

is this just one VSA and you are using it as a remote snapshot target?  If so, I assume it is designated as thin provisioned?  Dedupe compression definitely depends on your data, but it sounds like you have highly compressable data and could benefit from that feature.

 

If this is just for a remote backup snapshot and you can control when the snapshot is going to run and when dedupe is going to run so you don't run into contention issues with them running concurrently, then I could see the benefit of trying to add a layer of compression.

 

Backing up the remote VSA on the otherhand seems silly.  If you really want a 2nd layer of protection for those snapshots, you should just add a 2nd VSA or really you should backup your data correctly and not just use snapshots as most vendors do not consider snapshots as backups.