Using intel Optane P1600X for write cache

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Dichotomy
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Using intel Optane P1600X for write cache

Post by Dichotomy »

Hello, fellows!


I have just purchased intel Optane P1600X to be used as cache drive and trying to figure out how to use it most properly.

I have few consideration I would like to share.

1) Optane P1600X has some insane TBW. I assume that means it's best should as a write-through (Defer-Write) cache.
2) It has extremely low read response time (7ns) and therefore very fast read speed in short queues (240Mb/s 4KQ4) - so to use it for caching another SSD is very proper also.
3) However this drive has low linear read/write speed. (Less that 2GB/s) While my main SSD drive has about 7GB/s. On the other hand there are not so much scenarios when linear speed is impotant on home machine. Exept, maybe, Cyberpunk installation 120GB or working with video files. Do I understand correctly that in this scenarios it's better to torn off Defer-Write?
4) Impotant one. How safe is to have an L2 cache Defer-Write enabled? Do I understand corerctly that having L2-only SSD write cache enabled does not affect the integrity of the written data compared to writing directly to SSD in case of - for example - power shutdown or system hang? I mess with overclocking sometimes.



All-in-all my main question how to use this drive most efficiently without taking any additional data integrity risks.
So far I think I should set up DEFAULT write cache for Optane SSD but NOT for L1.

Will it be proper use for this drive?
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Re: Using intel Optane P1600X for write cache

Post by Support »

Dichotomy wrote: Sat Jan 14, 2023 6:48 pm 4) Impotant one. How safe is to have an L2 cache Defer-Write enabled? Do I understand corerctly that having L2-only SSD write cache enabled does not affect the integrity of the written data compared to writing directly to SSD in case of - for example - power shutdown or system hang? I mess with overclocking sometimes.
Well, currently the risk is same whether you use L1 cache or L2 cache. For more details, please see
https://www.romexsoftware.com/en-us/pri ... write.html
Dichotomy
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Re: Using intel Optane P1600X for write cache

Post by Dichotomy »

Support wrote: Tue Jan 17, 2023 8:12 am Well, currently the risk is same whether you use L1 cache or L2 cache.
Why? L1 is wiped if power is down, while L2 is permanent memory and saves contained info.

Do I understand smth incorrectly?
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Re: Using intel Optane P1600X for write cache

Post by Support »

The index database for cached data is kept in the memory. It requires fast access and it will be frequently updated. So currently we store it in the memory.
Dichotomy
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Re: Using intel Optane P1600X for write cache

Post by Dichotomy »

Support wrote: Fri Jan 20, 2023 4:12 am The index database for cached data is kept in the memory. It requires fast access and it will be frequently updated. So currently we store it in the memory.
Did I understand correctly that in case of an unexpected power loss all unflushed deferred to-write data in L2 cache will be lost or spoiled even if L1 cache is off?
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Re: Using intel Optane P1600X for write cache

Post by Support »

Currently, yes.
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