[Feature request] Hybrid Write Topic is solved

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cichy45
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Joined: Sun Oct 14, 2018 3:34 pm

[Feature request] Hybrid Write

Post by cichy45 » Sun Apr 14, 2019 5:23 pm

Hello. Recently one idea appeared in my mind - hybrid write. So, lets say you have (actual numbers not important) 500GB HDD that can write data 100MB/s and 60GB SSD as L2 Read/Write cache that can write data at 200MB/s. Deffer-Write is disabled, so with current PrimoCache writing to HDD is not accelerated but is cached on SSD for future reading.

What it you could have Hybrid-Write? What I mean by hybrid-write. So, your 500GB HDD can write data at 100MB/s, so even with SSD cache (Deffer-Write disabled) you are limited to 100MB/s write to cached volume. With Hybrid-Write any data that could not be written to HDD would be written to SSD instead. So, if you have USB3 pendrive with read speed 200MB/s, with Hybrid-Write you would copy from pendrive to cached volume at 200MB/s, 100MB/s going to straight to HDD and 100MB/s cached by SSD temporarily. It is not complete deffer-write, as SSD is ingesting data that HDD is not able to take. It could even be merged with current mechanism, so 100MB/s going to HDD and all data at 200MB/s going to SSD so all write-data is cached, not 50%. You could call it realtime buffer.

Something similar is implemented in Windows (you get full copy speed of 200MB/s despite disk being 100% active as Windows is caching data in RAM and is dumping it to HDD in background after copying "is completed"). Hybrid-Write would allow you to have this feature but with much higher data limit (as big as your allowed L2 Write size) and data not being damaged after powerloss (as it is cached on SSD, not RAM like windows do).

What do you think about this? Is this even possible to implement?

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support
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Joined: Sun Dec 21, 2008 2:42 am

Re: [Feature request] Hybrid Write

Post by support » Thu Apr 18, 2019 7:07 am

cichy45, thank you for your suggestion!
This is still a kind of defer-write. And please note that Windows default write behavior is also a kind of defer-write, with 2 second latency.
I think the key point here is to support data restore after power loss. We are working on it.
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Romex Software Support

cichy45
Posts: 30
Joined: Sun Oct 14, 2018 3:34 pm

Re: [Feature request] Hybrid Write

Post by cichy45 » Thu Apr 18, 2019 1:51 pm

Thank you for reply. Yes, I think that data protection in case of power loss and merging write speed of cache and cached volume would be beneficial.

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