WAN accel not adhering to cache size limit

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Re: WAN accel not adhering to cache size limit

Veeam Logoby foggy » Fri Feb 06, 2015 11:48 am

Alan, you definitely do not need WAN acceleration on such a fast link. It is designed for slow and busy links with little bandwidth available (when network is the real bottleneck, typically under 100 Mbps).

As to the cache size recommendations, you can find those above (though they are for v7, but still apply).
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[MERGED] Wan acceleration and SSD cache

Veeam Logoby verre » Fri Mar 20, 2015 8:12 am

Hi everybody, I am setting up a wan acceleration between two sites in order to accelerate the backup copy job. I know that it is necessary to have an ssd datastore in the target site in order to cache the data. I wanted to know if there are any prerequisites or best practices about the sizing and the location...is there anywhere a calculator? And moreover I need to know if it is necessary to have also an SSD cache in the primary site and if it must have the same size of the target cache. Thank you.
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Re: Wan acceleration and SSD cache

Veeam Logoby Shestakov » Fri Mar 20, 2015 8:58 am 1 person likes this post

Hi Valentino,
verre wrote:I wanted to know if there are any prerequisites or best practices about the sizing and the location...is there anywhere a calculator?

The more space you allocate, the more repeating data blocks will be written to the global cache and the more efficient WAN acceleration will be. By default, the size of the global cache is 100 GB and it is recommended to allocate 20GB per 1TB of source data, but not less than 40 GB.
verre wrote:And moreover I need to know if it is necessary to have also an SSD cache in the primary site and if it must have the same size of the target cache.

The global cache size is specified per source WAN accelerator. That is, if you plan to use one target WAN accelerator with several source WAN accelerators, the specified amount of space will be allocated for every source WAN accelerator that will be working with the target WAN accelerator and the size of the global cache will increase proportionally.
Thanks.
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Re: Wan acceleration and SSD cache

Veeam Logoby verre » Fri Mar 20, 2015 9:10 am

Tnahk you.... 100G plus 20G every 1T? Is it correct?
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Re: Sizing WAN Accelerator Cache

Veeam Logoby Shestakov » Fri Mar 20, 2015 9:21 am 1 person likes this post

Yes, 100GB + additional 20GB per 1 TB
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[MERGED] WAN Accelerator Drive Full

Veeam Logoby Murigar » Wed May 06, 2015 6:20 pm

I am using a one to one WAN Accelerator. I have the backup infrastructure setup at both sites. Each site lists its self and the other.

They are configured to use 150GB on a 200GB drive.
On the target end I am seeing the GlobalCache using the 150GB. But, I have Send using 36GB.
On the source side the GlobalCache is small, ~3Gb but the Digests are 209GB.

I'm sure there are many variables but do these metrics sound correct?
Should I set this down to 100GB instead of 150?
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Re: WAN accel not adhering to cache size limit

Veeam Logoby foggy » Wed May 06, 2015 8:52 pm

Please review the thread above for the cache size recommendations. For the source side please also consider additional 20 GB of free space per 1 TB of source VM data for digests.
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[MERGED] WAN Accelerator Configuring

Veeam Logoby rpedrazzini » Fri May 22, 2015 6:29 am

Good morning

My name is Ruggero Pedrazzini and work in the Municipality of Pavia, Italy.

I wanted to ask some questions about the setup of the Local and Global Cache for WAN Accelerator Veeam 8 Update 2.
Our infrastructure is will constitute to 1 cluster with 3 Host Esxi 5.5Up2 and 30 VM (Windows XP and Seven - Windows Server 2003,2008,2012 -
Linux: Debian, Centos, Ubuntu).
To determine the disk space to be allocated to the CACHE Wan Accelerator i have been using this methodology:

20 GB x 8 S.O. (5 Microsoft + 3 Linux) = 160 GB
20 GB x 12 TB (space occupied by Backup) = 240 GB

Tot Space CACHE 400 GB

Questions:

1) The space of 400 GB is to be assigned to both the LOCAL CACHE that the GLOBAL CACHE?

2) During configuration of CACHE SIZE, specifying a value 400 GB with disk space of 450 GB (vmdk), you receive the following message:
"The selected volume may have insufficient free disk space for storing digests of Transferred date.
Make sure you are meeting system requirement for free disk space available to WAN accelerator. "

How can I fix?

Thank you.

Ruggero
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Re: WAN accel not adhering to cache size limit

Veeam Logoby Shestakov » Fri May 22, 2015 8:37 am

Hello Ruggero,
1) It`s a global cahce. Could you clarify what you mean by the local one?
2) Recommendation is to assign 100 GB + 20 more GB per 1 TB of source VM data for digests. Looks like you have 20 TB of source data. Is it correct?
Please also review the posts above. Thanks
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Re: WAN accel not adhering to cache size limit

Veeam Logoby rpedrazzini » Fri May 22, 2015 9:21 am

Hello,

GLOBAL CACHE is WAN Accelerator TARGET (WAN Accelerator DR)

LOCAL CACHE is WAN Accelerator SOURCE

The 20 TB match the disk space used by backups, while the 30 VM occupy a space of 7 TB

Thank you
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Re: WAN accel not adhering to cache size limit

Veeam Logoby Shestakov » Fri May 22, 2015 12:48 pm

Thanks for the answer, Ruggero.
We usually use terms Source WAN accelerator and Target WAN accelerator global cache.
In your case the recommended cache size is 7*20+100=240 GB
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Re: WAN accel not adhering to cache size limit

Veeam Logoby rpedrazzini » Mon May 25, 2015 6:44 am

Thanks for the answer, but i a further question


In tests I have often found the following message:
"The selected volume may have insufficient free disk space for storing digests of Transferred date.
Make sure you are meeting system requirement for free disk space available to WAN accelerator. "


I solved by configuring CACHE SIZE to 250 GB with a disk space of 500 GB VMDK thus leaving 250 GB Free.

But I can not understand why.

You could explain it?

Thank you.

Ruggero
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Re: WAN accel not adhering to cache size limit

Veeam Logoby Shestakov » Mon May 25, 2015 10:00 am

Ruggero,

The warning appeared because the disk was running out of free space.
I guess your jobs worked well, you just had the warning to be aware of.

Thanks!
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Re: WAN accel not adhering to cache size limit

Veeam Logoby Scol » Thu Jun 04, 2015 2:09 pm

Hi everyone,

I am have the same question as Ruggero, and there are no answers yet.

rpedrazzini wrote:In tests I have often found the following message:
"The selected volume may have insufficient free disk space for storing digests of Transferred date.
Make sure you are meeting system requirement for free disk space available to WAN accelerator. "


This message appears when selecting the cache size while configuring the WAN Accelerator.
What is the ratio used here ? Is this a false alarm ?

Case #1 If I use the following settings : WAN disk size 100GB, Global Cache size 75GB, Free Space 25GB, I don't have this message.
Case #2 If I use the following settings : WAN disk size 175GB, Global Cache size 110GB, Free Space 65GB I have this message.

In case #1 I have 25% of free space, in case #2 37%.
I just don't get it, how much free space is needed ?

Also if I understand everything well, in case I only have one source and one target, both cache size should be the same (on source and target) ?

Regards,

Raphael
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Re: WAN accel not adhering to cache size limit

Veeam Logoby Shestakov » Fri Jun 05, 2015 11:15 am 1 person likes this post

Hi Raphael,

The initial logic is very straightforward: GUI should warn if the free space after WAN cache allocation is less than 20GB, no linkage to % of free space.

However the warning might work incorrectly when editing the accelerator. In your cases provided, have you just created the accelerator in the 1st case and edited in the case #2? If my guess is correct, you will have a warning if try to edit the 1st accelerator, even keeping the same numbers. I`ve sent the issue to QA team for extra-testing.
One way or the other it`s just a warning. Ignore it if you have more than 20GB of free space.

Thanks!
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