Architecting Storage (wither to NFS or...)

Channels DVR Server
#1

I'm on the verge redoing my NAS here and want to re-visit some technology choices. I'm running Channels DVR in a container on Docker on a Linux host.

I was blessed with several Western Digital MyCloud EX2. When I decided to try Channels DVR out seriously, I dedicated one of these to it (6 TB RAID1). Initially I set up an NFS share and did some performance testing by copying folders around. Copying 27 GB to this NFS share took 17 minutes, 212 Mbps. That's fine for recording or playing back one thread, but I'm afraid what will happen with more simultaneous recordings, commercial detection, etc. I tested the same copy to an iSCSI volume on a different MyCloud EX2, and got 9.5 GB in 3 minutes, or 422 Mbps. So, I scrapped the NFS share and spun up a 6 TB iSCSI volume.

It has performed fine, but I have two issues here:
(1) It's not flexible; I dedicated the full NAS to it, I can't borrow from it, and expanding it (5 years from now) will not be fun.
(2) every 2 or 3 months, the iSCSI volume drops offline on the host... either briefly, and Linux marks it as read only, or completely. Each time it's a pain, where I pretty much have to shut Docker down, reboot the server, fsck the volume and remount it and start everything back up.

So... for those of you using a NAS for file storage (for DVR operations... and any static media storage), what technology are you using? NFS? iSCSI? Something else? How happy are you with it?

Something of note... I direct EVERYTHING in the Channels DVR container to this mount point, so this is configurations and DVR recordings. I have other media on a different iSCSI volume on a different NAS. My thought is to combine these onto one newer, larger NAS, probably with RAID 5. Still different shares between static media and the DVR storage, but likely on one RAID 5 instance on the NAS. Still also thinking about backup for the new NAS... whether to backup to the older MyCloud EX2s until they die, or get something like AWS Glacier.

#2

I've been using NFS for years now with various NAS configurations with no issues per se. Today that means a Unifi UNAS Pro in the past that might have meant Synology or a Dell SAN advertising nfs mounts.

One constant across all of the NAS platforms I've used has been autofs. If you're not familiar with autofs it basically allows the nfs volume to dynamically mount when accessed so, if for some reason, the device goes offline and comes back or the server and NAS boot up in the wrong order then autofs corrects for that.

#3

Thanks for the response. autofs sounds great... but I seem to be having some issue that's not letting the iSCSI volume go, so I wonder if it would let the NFS file system unmount when the timeout occurs.

Normally when the issue occurs, the volume remains online, but read-only. I stop the Channels container to make sure it's free so that I can dismount it (nothing else uses this volume). I dismount it so that I can run fsck, but then fsck says it's still busy. I've stopped Docker completely, and that has helped once. Most of the time, volume is still busy. Maybe I just need to rebuild the linux host...

#4

I use NFS mounts for media for Channels DVR and Plex. The NFS mounts are solid and don't go offline. WD-PR4100 NAS.

#5

So long as nothing is trying to access the share then autofs does not try to remount it. In my use case, I only allow Channels to access the share hence if Channels service is shutdown then autofs doesn't care to remount it. If I cd into the directory or restart the Channels service then it would auto mount it.

#6

iSCSI for a DVR is an overkill and a waste of space especially when backed by a ZVOL. Just stick with NFS. You are trying to prematurely optimize storage without any need to do so.

#7

I've used SMB on TrueNAS, Unraid and also a Windows Server. It's super easy to expand and upgrade storage pools on all of them. NFS should be about the same though write don't have to commit so there is a data loss risk if there is a failure. Power is probably the most common failure so use a UPS. iSCSI can be expanded on some storage devices. If you want the fastest commercial skipping you want a wide vDEV of spinners. SSDs work great and use little power. SSD crashing and or storage tearing are other options for fast commercial skipping. A CPU with a lot of cores also makes a big difference.