I wonder if cache works (for me)

[aarbee]

Hi,
As the title says does cache of the M2 SSD work on a TVS-x73 in general. Or does it work for me?
I really doubt if Cache works works on the stated device.
And secondly is it maybe me, as about the only person using the NAS for fileserver, running 2 VM's (hardly used), and a plex server. 1-2 streams, but even that hardly used.
I use the file system more as an archive. Sometimes updating or adding files. But not weekly the same.
Does it work for the Virtual Machines?
Otherwise I am thinking about moving the Virtual Machines towards the M2 SSD, which are then working as a regular Raid 1 or perhaps Raid 0.

[Trexx]

Hey Rob,

I would say yes M2 SSD's work in general on the x73 family (although there is the whole separate thread about SSD cache perf issues).

A better question though might be, how beneficial is SSD caching in my use case based on how I have it configured.

For background, I believe the QNAP cache implementation is based Facebook's Flashcache codebase. Here is a good background primer on it: http://assets.en.oreilly.com/1/event/45 ... tation.pdf

Let's look at your different usage types from a READ view:

Media Streaming via Plex
For video streaming (basically Sequential Read activity), you are unlikely to see any benefit from the cache unless you have 2 different streams playing the same file relatively close to each other where you would get a read-hit out of the cache. And that is also dependent on how you configured the Cache to begin with.

Now personally I do see some benefit on the read cache when running Kodi directly off the QNAP via HDMI in terms of Kodi startup time, media thumbnail population, etc... which is likely coming from read caching itself. Also mySQL db seems to get some benefit.

File Server
Again you aren't going to see much benefit on the read side unless you are accessing say a large Access DB, etc. where it is a large file that is repeatedly access.

VM's
Here you probably would see some good benefit of the read caching as the VM's are really just a big large file from the NAS view and will frequently use the same parts (VM files within it especially for OS), but since you have infrequent usage you probably won't notice it as aren't using it that often.


On the WRITE side -> generally everything is flowing from NW/NAS -> CACHE -> DISK. So you can get some benefit on the write side for local things (VM's, internal mysql, etc.), and POSSIBLY some benefit on NW stuff if running either 10GbE, or multiple 1GbE port trunked (802.3ad) connections to multiple hosts under load.

The main thing here is driving more than 110MB/s of write traffic (which a 673 with decent HDD can handle directly). If you are under 110MB/s, then really the 1GbE bottleneck will get you before the SSD can really give you benefit over writing straight to HDD.

Hope that helps,
Paul

[aarbee]

Thanks Paul.
So the only thing that cache would work for me, was the reason for me to get rid of the caching.

Good explanation.

Good harddisk, yeah really, with notebookdisks for over 4 years. What was the reason we need NAS harddisks?
As long as it works. What else to do with the old disks. Using them until they say crack.

Robb

[Trexx]

Thanks Paul.
So the only thing that cache would work for me, was the reason for me to get rid of the caching.

Good explanation.

Good harddisk, yeah really, with notebookdisks for over 4 years. What was the reason we need NAS harddisks?
As long as it works. What else to do with the old disks. Using them until they say crack.

Robb

Use you notebook drives in USB docks for backup drives. Then put some nice HGST deskstar NAS drives in their place.


Sent from my iPhone using Tapatalk

[aarbee]

HGST is good. I know.