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LSFS Cache

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LSFS Cache

Postby KLSsandman » Fri Mar 14, 2014 11:44 am

Hi,

When creating a new LSFS device of 8TB it says I need around 60GB RAM for caching (with no dedupe or autodefrag), and as I result of me only have 24GB spare it can only create a 6TB disk. With dedupe and defrag enabled it wants over 80GB RAM free!

Whats the ratio? I'm trying to work out how much ram our production starwind servers would need to create LSFS disks. Does it really need all that ram?

We currently have:

3 x 1.17TB datastores
3 x 2.64TB datastores

Thanks
Simon
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Re: LSFS Cache

Postby anton (staff) » Fri Mar 14, 2014 11:54 am

It's not a cache these are hash and metadata in-memory tables actual LSFS cache (sitting below dedupe engine and thus working with deduped data) is quite different thing.

LSFS needs aroung 5GB for every 1TB of served data.

We work with post-V8 with a fixed 4KB blocks (compare this with floating 32KB+ off-line MS dedupe and dynamic ZFS blocks) and need ~6 bytes for hash entry (ZFS needs 200+ bytes *OR* would increase dedupe blocks resulting not so good savings) I don't think LSFS is a real "memory pig" here :)

KLSsandman wrote:Hi,

When creating a new LSFS device of 8TB it says I need around 60GB RAM for caching (with no dedupe or autodefrag), and as I result of me only have 24GB spare it can only create a 6TB disk. With dedupe and defrag enabled it wants over 80GB RAM free!

Whats the ratio? I'm trying to work out how much ram our production starwind servers would need to create LSFS disks. Does it really need all that ram?

We currently have:

3 x 1.17TB datastores
3 x 2.64TB datastores

Thanks
Simon
Regards,
Anton Kolomyeytsev

Chief Technology Officer & Chief Architect, StarWind Software

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anton (staff)
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Re: LSFS Cache

Postby KLSsandman » Wed Mar 19, 2014 12:29 am

Hi Anton,

Thank you for your reply, I understand it now. Home lab will struggle to get enough ram to provide for 8TB with server grade motherboards :cry: Production will be fine though.

Thanks
Simon
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Posts: 8
Joined: Tue Mar 11, 2014 2:06 pm

Re: LSFS Cache

Postby Anatoly (staff) » Thu Mar 20, 2014 10:50 am

Well, you can always test if that`ll work for you, or you can try to use smaller storage capacity and after you`ll get enough of RAM - expand it.
Best regards,
Anatoly Vilchinsky
Global Engineering and Support Manager
www.starwind.com
[email protected]
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Re: LSFS Cache

Postby Bhai » Mon Jan 12, 2015 10:38 am

When creating a new LSFS device of 8TB it says I need around 60GB RAM for caching (with no dedupe or autodefrag), and as I result of me only have 24GB spare it can only create a 6TB disk. With dedupe and defrag enabled it wants over 80GB RAM free!



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Last edited by Bhai on Fri Nov 16, 2018 7:29 am, edited 2 times in total.
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Re: LSFS Cache

Postby anton (staff) » Mon Jan 12, 2015 1:46 pm

It's not a cache really these are in-memory hash tables. 5GB of RAM for 1TB of served capacity. Turn off dedupe to reduce requirements.

Bhai wrote:When creating a new LSFS device of 8TB it says I need around 60GB RAM for caching (with no dedupe or autodefrag), and as I result of me only have 24GB spare it can only create a 6TB disk. With dedupe and defrag enabled it wants over 80GB RAM free!
Regards,
Anton Kolomyeytsev

Chief Technology Officer & Chief Architect, StarWind Software

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anton (staff)
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