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arrenwu
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About Mechanisms of Different Modes for Deferred Write

Post by arrenwu »

I've checked the explanation on the website.
https://www.romexsoftware.com/en-us/pri ... ation.html

Native is easy to understand. It's basically saying that Primocache will start to write deferred data to the disk after the specified Latency.
My questions are about the other modes.

(a) For Intelligent, Idle-Flush, Buffer modes, they are stated as Native modes plus some other conditions. However, I would like to know exactly the deferred data is treated according to those additional conditions.

For example, we consider Intelligent mode, which is Native mode plus writing 10%~20% of deferred data into disk on Windows idle when deferred data amount reaches 90% of cache size. Latency is set to be 10 sec.

Suppose I have 4GB L1 cache for write data and no other cache for write. What will Primocache deal with the deferred data if
(1) the deferred-write reaches 2GB in a 10-sec write
(2) the deferred data reaches 3.8GB in a 10-sec write ?

In particular, I'm curious about the case of (1) since it says Intelligent mode writes deferred date only if the amount reaches 90% of cache size. Will these deferred-write data remain as deferred-write in the cache for a very long time if no other incoming write data?

(b) It's stated that Average mode will average the amount of deferred data over a period of time and smoothly writing data into disk to avoid sudden heavy disk activities. How does it works according to the specified Latency?
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Support
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Re: About Mechanisms of Different Modes for Deferred Write

Post by Support »

I'm sorry for the confusing description on these terms.
arrenwu wrote: Sun Aug 23, 2020 10:22 pm (a) For Intelligent, Idle-Flush, Buffer modes, they are stated as Native modes plus some other conditions.
Here the logical relation is Native mode OR other conditions. When each one is met, flushing will be triggered.
arrenwu wrote: Sun Aug 23, 2020 10:22 pm (b) It's stated that Average mode will average the amount of deferred data over a period of time and smoothly writing data into disk to avoid sudden heavy disk activities. How does it works according to the specified Latency?
Latency roughly specifies the "a period of time" for averaging. However the latency is internally limited to 120s. This means even you set latency greater than 120s, the average mode will still use 120s.
Tobiwan
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Re: About Mechanisms of Different Modes for Deferred Write

Post by Tobiwan »

Thank you for the explanation, that's something I never understand 100%, especially as non native English speaker.

What is the default Windows latency for data writing? Zero? And what is the best mode to use at the end with a normal PC (does it make a different for SSD and HDD, Gaming)?
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Re: About Mechanisms of Different Modes for Deferred Write

Post by Support »

Windows default write latency is 2s. For PrimoCache write mode, usually you may choose native or intelligent mode.
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