SSD Cache - no advantage for me?

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dbbarron
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SSD Cache - no advantage for me?

Unread post by dbbarron » Tue Aug 07, 2018 7:53 pm

I have a SOHO setup DS-918+.
Main daily uses are a Plex server, time machine backup, and security cam recording/management.

I assumed based on my research that these are all essentially streaming uses and an SSD Cache would provide no performance advantage (I'm looking to generally optimize performance, particularly for Plex).

However, the 'SSD Advisor' indicates a recommended 186.2Gb with 14-45Gb/day of total file size and about 1000-5000 files/day.

Hot=23Gb
Warm=162Gb
Cold=647Gb
Archived=4TB.

Is this recommendation appropriate? I suspect this may just show total data accessed rather than how often the same files are accessed which is more accurate for cache prediction.

Can someone please explain.

THX!

pgotze
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Re: SSD Cache - no advantage for me?

Unread post by pgotze » Tue Aug 07, 2018 9:41 pm

I dont think for PLEX usage will be bottleneck in data read from discs. So i guess you will have no real benefit of that.

That you should more or less check in real, to make some real stress tests using your average streaming test scenario and check, if its streaming without issues and if not, check, what is the bottleneck. If you use PLEX seriously, first you should use PLEX subscription and use HW transcoding.
DS918+ (16GB RAM, 2x4TB SHR, 2x256GB read/write cache) business, DS916+(8GB RAM, 3x2TB SHR, 1x1TB single) home, DS213j(512MB RAM, 1x1 TB single, 1x 500GB single) off-site backup

dbbarron
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Re: SSD Cache - no advantage for me?

Unread post by dbbarron » Tue Aug 07, 2018 9:47 pm

I should have added that I am using HW transcoding already.

pgotze
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Re: SSD Cache - no advantage for me?

Unread post by pgotze » Wed Aug 08, 2018 2:26 pm

Well then just run streams like you expect in real life on your target devices and check whole chain (NAS CPU - HDD volume - NAS LAN interface - router - wifi or lan of clients). And you will see, where the bottleneck is. You have to really check by your own, there is no generall advice, valid for all in such topic.
DS918+ (16GB RAM, 2x4TB SHR, 2x256GB read/write cache) business, DS916+(8GB RAM, 3x2TB SHR, 1x1TB single) home, DS213j(512MB RAM, 1x1 TB single, 1x 500GB single) off-site backup

itsjasper
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Re: SSD Cache - no advantage for me?

Unread post by itsjasper » Thu Aug 09, 2018 12:36 am

You’ll definitely see an improvement in the Plex web front end, things like the movies and tv shows artwork and internal databases will get cached.

mervincm
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Re: SSD Cache - no advantage for me?

Unread post by mervincm » Thu Aug 09, 2018 2:06 am

itsjasper wrote:
Thu Aug 09, 2018 12:36 am
You’ll definitely see an improvement in the Plex web front end, things like the movies and tv shows artwork and internal databases will get cached.
This is what I was going to say. I have my plex server installed on an SSD volume now, and it is much snappier than it used to be. My Plex Library folder is only 50GB but it has 260,000 files. loading up all that metadata to construct the client experience is much faster from SSD than from HDD. SSD volume works better for me than SSD cache did, but it you don't have the slots to spare, I would definitely try SSD cache.
1815+ (factory patched board) 4GB 5x6TB WD RED

Squozen
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Re: SSD Cache - no advantage for me?

Unread post by Squozen » Thu Aug 09, 2018 10:10 am

I think a cache is a waste of money after having tried it and would recommend adding more RAM to the NAS instead.

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