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L2 Cache questions

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L2 Cache questions

Postby DUOK » Mon Nov 25, 2013 10:48 pm

Hello everybody,

I'm testing the beta, especially the L2 cache and have several questions about what would be the right thing for safety and performance.

Without HA, is it totally safe to use L2 cache in writeback mode with SSD ? (The SSD with power-fail capacitors and RAID1, of course)

Using same SSD (eg Intel S3700). Is Starwind L2 cache as safe as the LSI CacheCade with flashback battery and all in writeback?

You think that would gain some performance by adding an L3 Cache (eg CacheCade) to L2 + L1 Starwind's cache?


By the way I'm having some problems using L2 cache with LSFS drives, I'll try a bit more and I inform.
DUOK
 
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Re: L2 Cache questions

Postby anton (staff) » Wed Nov 27, 2013 12:07 am

For non-HA config we'll recommend to turn StarWind flash cache OFF, use minimal amount of a RAM cache in Write-Thru mode and use Windows built-in flash cache
(after we'll fix StarWind to work on a Storage Spaces, that's closer to release). We don't see non-HA as a production and a) don't want to be responsible for "flaw by design" issues and b) there's no point in using StarWind cache when it's not distributed. Making long story short: on a stripped down config (1 node) Windows flash cache is better because
it's kernel-level one (StarWind runs most in user land). With a multiple nodes StarWind is better becase it's distributed (faster as VM moved to another host starts from a "hot" state and has multiple MPIO paths and is safe as there are multiple copes of the same BLOB - Microsoft fails to do everything listed).

Do not use hardware cache with StarWind as it's pointless. Longer I/O path = higher latency. + we don't control data submitted to CC you use. After CC reported "OK" we have no idea where data actually is - inside CC cache, on a platter or in the middle of the nowhere.

Sure please tell us about LSFS + cache issues!

Thanks!

DUOK wrote:Hello everybody,

I'm testing the beta, especially the L2 cache and have several questions about what would be the right thing for safety and performance.

Without HA, is it totally safe to use L2 cache in writeback mode with SSD ? (The SSD with power-fail capacitors and RAID1, of course)

Using same SSD (eg Intel S3700). Is Starwind L2 cache as safe as the LSI CacheCade with flashback battery and all in writeback?

You think that would gain some performance by adding an L3 Cache (eg CacheCade) to L2 + L1 Starwind's cache?


By the way I'm having some problems using L2 cache with LSFS drives, I'll try a bit more and I inform.
Regards,
Anton Kolomyeytsev

Chief Technology Officer & Chief Architect, StarWind Software

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