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How do external drives behave in relation to internal NAS storage/management?

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Not sure the best place to ask this.

I have a DS420J 4 bay NAS, primarily used for my Plex server and data backups (among a few other things). I currently have 8x6x6 TB Iron Wolf NAS drives in a single volume with SRH and an extra 1 TB SSD JBOD. I have my Plex app and metadata stored on the SSD due to the increased performance I have seen vs. having it installed on the large pool (7200 RPM cap). I am sitting at about 85% used storage of my available 10.8 TB on the primary volume. As such, I am pre-planning my next storage upgrade and am curious about my options while staying with the current hardware. The future plan will be a NAS upgrade, but this little beast has been chugging along so perfectly I want to push it as far as I can.

If I was to remove the 1 TB drive and replace it with another 8 TB Iron Wolf, I would jump to 20 TB available storage. https://www.synology.com/en-us/support/RAID_calculator?hdds=6 TB|6 TB|8 TB|8 TB This increase would last me for quite some time ahead of a full NAS upgrade with more bays. In order to do this, I would obviously need to remove the 1 TB SSD to be replaced by the new drive. I have na external enclosure for this drive that can connect over USB to the NAS.

My question: I am finding somewhat conflicting information on how external drives are intended to be used/what their capabilities are when connected to the USB 3.2 port. It seems the intended functionality for backups (which makes sense). Am I able to utilize a USB connected drive and have it function in a similar manner to it being internal? Are you able to install apps from the Package Center to an external drive? Create volumes? I assume there will be some performance degradation due to the translation from SATA to USB, then back to SATA, but I anticipate the SSD will still perform better than adding the app back to the main pool. I just don’t know if I am potentially missing something with my evaluation. Those that have more experience with USB connected drive with their NAS, I would love to hear your experience. Thanks!

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2 comments
  • Am I able to utilize a USB connected drive and have it function in a similar manner to it being internal?

    technically speaking, there isn't much difference between internal and external devices they are both accessible from the operating system BUT operating systems could limit their useability. For example, I noticed that I cannot install Windows on an external USB device even if that device is an NVME SSD in a USB enclosure.

    This also includes if your Synology actually allows an external device to be used for application data. If you use Docker you could map any volume to the internal container configuration (but from what I can find the DS420J doesn't support docker?!)

    But speed is another thing. Internal connections are usually faster than external devices. This, however, might not make much of a difference because the reason you put the Plex configuration an metadata on an SSD is not necessarily because of how fast it is but rather because of the increases access time of files. There is just not a read/write arm that has to travel back and forth on a disk to read your data.

    Are you able to install apps from the Package Center to an external drive? Create volumes?

    I don't use Synology drives so all I can do is google and I found this

    Those that have more experience with USB connected drive with their NAS

    As with most external devices, keep in mind that they have features to conserve power so they can power down or go idle at some point. This might not be much of an issue with Plex since log files are written constantly. But this is also the next thing, that external device would be online all the time your server would be online, adding to your overall power consumption and might not even be designed to run all the time.

    Personally, I would rather have your media files stored on the external device instead of application data and configuration. I would have suggested to replace a drive with a larger one (one 6TB drive with a 16TB) but this doesn't seem to give you that much storage space in comparison than adding a new drive...

    • Thank you for the detailed reply and thoughts! This is definitely helpful information and you make very good points.

      but from what I can find the DS420J doesn’t support docker?!

      You know, it’s funny. I have been considering taking the dive into Docker for some time, just to learn how it works and leverage its capabilities. I could have sworn I’ve seen a Docker app in Package Center previously, but when I just checked - no results. Interestingly, their documentation seems to include the DS420j as an approved model. I anticipate this is because I am still on DSM 6 and it is only currently supported on DSM 7. So, this is still something to consider. I appreciate the suggestion.

      that external device would be online all the time your server would be online, adding to your overall power consumption and might not even be designed to run all the time.

      Yeah, this is one of my concerns with moving it to be over USB. I mean, the SSD is already in the NAS (and is not a NAS grade SSD by any means, just an extra I had) so I don’t necessarily think the uptime will be an issue as I have a backup in case it dies anyway - more of how the added power and data translation that will have to occur and its effects. Might be a total non-issue. I suppose the only way to really know is to test it and find out :)

      To your final paragraph - That is a great point and part of the reason I wanted to make this post. The primary reason I want to go with the second 8TB is that, due to SRH, I can have no wasted space with the 6x6x8x8 configuration and enough additional space to last me until I am ready to upgrade to a more mid range box with large drives. Since I want to use it to expand the primary volume for more Plex storage, I don’t know that an external drive is going to do the trick even if I can swap drives out (though as noted, maybe with Docker. I will definitely be looking into that more). The downside to the RAID though and my current drive sizes is definitely that, yeah, I can’t just buy a giant drive and throw it in there to solve the problem.

      Thanks again for the reply!