StarWind iSCSI SAN
StarWind Native SAN for Hyper-V
 

Max Cache Size

Pure software-based VM-centric and flash-friendly VM storage (iSCSI, SMB3, NFS, iSER and NVMe over Fabrics) including free version. Same software embedded on StarWind ready nodes.

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Max Cache Size

Postby KPS » Fri Mar 15, 2019 7:47 am

Hi!

In the past, there have been some limitations in the L1-cache size of a HA-cluster.
Are there any improvements? Whats the maximum size, you recommend?

Regards,
KPS
KPS
 
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Re: Max Cache Size

Postby Oleg(staff) » Fri Mar 15, 2019 1:58 pm

Hi!
Please check this KB article.


"The size of L1 cache should be equal to the amount of the average working data set. The total amount of L1 cache assigned influences the time required for system shutdown. Please make sure not to overprovision the L1 cache amount to avoid the service interruption and the loss of cached data.

In case of using L1 cache in write-back mode, UPS units have to be installed to ensure the correct shutdown of StarWind Virtual SAN nodes. If a power outage occurs, this will prevent the loss of cached data. The UPS capacity must cover the time required for flushing the cached data to the underlying storage."
Oleg(staff)
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Re: Max Cache Size

Postby KPS » Fri Mar 15, 2019 2:12 pm

Hi Oleg!

Thats quite vague...

In case of a HA-system, the loss of the cache should not be critical. What is the maximum size, you recommend?
KPS
 
Posts: 51
Joined: Thu Apr 13, 2017 7:37 am

Re: Max Cache Size

Postby Oleg(staff) » Fri Mar 15, 2019 2:49 pm

Hi!
Based on StarWind Best Practices, we recommend creating devices up to 5-6 TB in size. So, L1 cache should not be bigger than 5-6 GB per StarWind HA device.
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Re: Max Cache Size

Postby KPS » Fri Mar 15, 2019 2:51 pm

Hi!

So, if I have 30 TB, I would create 5 volumes with 6 TB and each one with 6GB L1-Cache --> 30GB L1-Cache?
KPS
 
Posts: 51
Joined: Thu Apr 13, 2017 7:37 am

Re: Max Cache Size

Postby Oleg(staff) » Fri Mar 15, 2019 3:04 pm

Yes, it should work. But do not forget about the amount of the average working data set. It can be even less.
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