Primocache questions

[80251]

I have to admit primocache is very impressive as to its list of configuration options and I've read of some unique uses of primocache (e.g. as a RAM disk that overflows to SSD storage as needed). Anyway, I asked my questions on the primocache technical support forum and got zero answers (maybe my questions are too dumb). I also read through the entire, mammoth manual for primocache.

Questions:

1. would it be useful to use a PCIe NVME M.2 SSD to cache slower SATA SSD's?

2. Should superfetch be turned off when using primocache?

3. Does primocache cache temp directories (as setup by the environment variables in system properties --> advanced system settings --> environment variables? If a volume has temp directories should it be excluded from caching?

4. my 2 TiB HDD's are set to a 512-byte cluster size (I thought, perhaps erroneously, the smallest cluster size was best for maximizing disk space). What block size should I use for primocache's cache volumes? The cache volume would
be quite large in my case (670.32 GiB) so I'm guessing NOT 512-bytes. Should I try 4K for the cache volume block size or even larger than that?

5. since the cache volumes have to be previously defined in windows and that requires the volume be formatted, how can primocache overwrite the previous formatting? Or is primocache's block size entirely independent of the underlying file system cluster size?

6. is the deferred writes setting analogous to a write-back cache?

 

[(00)]

Wow... All good questions. I will monitor this thread with you, and a wait the answers...

(00)

 

[R0H1T]

Useful yes but much better use for the PCIe SSD would just be to use it as a boot(?) drive.

No need, though generally prefect & SuperFetch both are unnecessary with SSDs.

Yes, it caches everything.

Check the settings, when you setup cache there's usually a recommended size ~ but memory overhead could be an issue there!

Can you reframe the question, the first part? Yes to the second one.

No, also be very careful with deferred writes! I've lost multiple Windows installations to that because even a simple BSOD could render your system unredeemable, of course backups & even system restore helps but they're not a mitigation really

Also I'd generally avoid Primo Cache unless you're working on lots of HDD's & they're slowing you down! Since I've moved almost exclusively to SSD (only) systems I don't need/use it anymore.

 

[oobymach]

Primocache is basically a deferred write, it caches the file and copies it slowly over time which you basically do anyway, it is a redundant software that isn't needed imo.

As for drive cluster size for hdd's a 4k cluster performs better than a 512b cluster both sequential and 4k.

 

[80251]

@oobymach
I've noticed, at least for the SK Hynix P31 Gold 1 TiB using the ATTO/iometer sequential reads benchmarks for this particular SSD that as the cluster size (not sure if this is the correct analysis or not) increases so does the MB/s read/written.
(as seen here: https://www.tomshardware.com/reviews/sk-hynix-gold-p31-m2-nvme-ssd-review/3)

So wouldn't it be better to have a larger primocache block size than 4K, at least for speed (and decreasing the CPU load/memory footprint)?

 

[oobymach]

Afaik higher than 4k cluster sizes do not improve performance but they do fill up the drive faster, 4k cluster is the optimal size for current windows builds, some ssd don't natively support 4k even if you select it they will run 512e(mulation) but there is no speed loss in a 512e setup.

 

[lexluthermiester]

it is a redundant software that isn't needed imo.

That depends on the use-case-scenario. The testing I did last year showed some very interesting results.

Should i buy primocache?

it tripled my SSD performance!

www.techpowerup.com

Should i buy primocache?

it tripled my SSD performance!

www.techpowerup.com

There is definitely some benefit to be had, but how it's used is an important factor.

 

[80251]

It would be nice to use deferred writes with the L2 cache, but I don't have a UPS.

 

[oobymach]

That depends on the use-case-scenario. The testing I did last year showed some very interesting results.

Should i buy primocache?

it tripled my SSD performance!

www.techpowerup.com

Should i buy primocache?

it tripled my SSD performance!

www.techpowerup.com

There is definitely some benefit to be had, but how it's used is an important factor.

Interesting, you got me curious enough to try it myself, looks good in cdmark but result was no improvement in copy speed between the 2 hdd's I selected for caching (I did not enable write deferring).

My 4tb wd black with an 8gb primocache.

 

[lexluthermiester]

Interesting, you got me curious enough to try it myself, looks good in cdmark but result was no improvement in copy speed between the 2 hdd's I selected for caching (I did not enable write deferring).

My 4tb wd black with an 8gb primocache.
View attachment 249942

Yeah that was similar to what I got. In many situations, most programs reading/writing between storage and RAM, this would be a godsend. Video editing comes to mind. I did run those tests with a quick video rerender with XMediaRecode and there was an improvement. Of course there are many scenario's I'd imagine Primocache will do nothing at all, system file management for example. Web browsing would likely improve some, but MMO gaming might not.

The benefit and utility of this program has to be explored by the parties interested in it's potential. The 30day trial makes testing it out trivial, so there is nothing to loose.

 

[80251]

One of the applications someone was using primocache for on their forums was a guy trying to minimize writes to his SSD. He did this by setting up a massive write only L1 cache that would only write out to the SSD L2 when it filled up. He was running some scientific application like F@H.

 

[lexluthermiester]

One of the applications someone was using primocache for on their forums was a guy trying to minimize writes to his SSD. He did this by setting up a massive write only L1 cache that would only write out to the SSD L2 when it filled up. He was running some scientific application like F@H.

That is a good example of an excellent use. UPS is a must in situations like that.

 

[80251]

UPS's must be really expensive these days, the ones I had would provide maybe 5 minutes of power for an old AMD K6-2 system and the batteries seem to only have a limited life even if they're never used (i.e. in a power loss situation).

 

[chrcoluk]

I have to admit primocache is very impressive as to its list of configuration options and I've read of some unique uses of primocache (e.g. as a RAM disk that overflows to SSD storage as needed). Anyway, I asked my questions on the primocache technical support forum and got zero answers (maybe my questions are too dumb). I also read through the entire, mammoth manual for primocache.

Questions:

1. would it be useful to use a PCIe NVME M.2 SSD to cache slower SATA SSD's?

2. Should superfetch be turned off when using primocache?

3. Does primocache cache temp directories (as setup by the environment variables in system properties --> advanced system settings --> environment variables? If a volume has temp directories should it be excluded from caching?

4. my 2 TiB HDD's are set to a 512-byte cluster size (I thought, perhaps erroneously, the smallest cluster size was best for maximizing disk space). What block size should I use for primocache's cache volumes? The cache volume would
be quite large in my case (670.32 GiB) so I'm guessing NOT 512-bytes. Should I try 4K for the cache volume block size or even larger than that?

5. since the cache volumes have to be previously defined in windows and that requires the volume be formatted, how can primocache overwrite the previous formatting? Or is primocache's block size entirely independent of the underlying file system cluster size?

6. is the deferred writes setting analogous to a write-back cache?

Hi, based on a quick crash course of primocache.

1 - I think for mainstream use you probably wouldnt notice it, NVME benches a lot faster but for real world use will probably not feel much faster, but the best answer is try it and see.
2 - Windows is supposed to automatically disable superfetch caching when a SSD is detected as its benefit is primarily of benefit to spindles. Bear in mind the the superfetch service is now renamed as it does more than just a pre emptive cache now. If primocache does any ram based caching I would consider disabling superfetch to avoid double caching. I dont think it does though.
3 - It would seem it does, but I only read the brief description, which implies it work similar to ZFS secondary cache.
4 - 512byte sectors are typically a bad idea now days, because drives are usually manufactured with 4k physical sectors and that they going to give you inferior performance, fragmentation anyway. I wouldnt go smaller than 4k on an SSD, so unless primocache documentation says other probably best to stick to 4k which is the default.
5 - no idea

Example: Reduce Wear on Solid-State Drives by Defer-Write

PrimoCache Help Documents - Example: Reduce Wear on Solid-State Drives by Defer-Write

www.romexsoftware.com

6 - It looks like some kind of caching and queue management system, so yes write-back.