Multiple concurrent reads of same file(s)

[SourceVisualisation]

I'm totally new to FreeNAS but am considering building a NAS box using it. I run a small 3D visualisation company and currently have a Qnap NAS which is a few years old. I'm wondering if building my own box will solve a limitation I think the Qnap one has:

When rendering 3D scenes with 3ds Max, and also when rendering multiple variations of the same video in After Effects, I often have a number of PCs all accessing the same reference files at exactly the same time. At times I find rendering slow to start and I wonder if the Qnap NAS has a limit to how many devices can read any one file simultaneously (I understand that NASs allow fewer devices to read a given file simultaneously than a Windows Server for example).

Can anyone tell me if there's a limit within FreeNAS? Or would it be more likely to be a hardware limit? If so, how should I spec a DIY FreeNAS box to try and avoid this issue?

 

[kdragon75]

I understand that NASs allow fewer devices to read a given file simultaneously than a Windows Server for example

Not sure where you got this from. At work we use NetApp for most of our storage and that supports 40,000+ users and for some applications im sure the same file is read by many clients at the same time. I would love to see a windows server do that from an NTFS volume.

You don't mention HOW the files are accessed. Are you using CIFS, AFP, SFTP, or something else? I'm guessing CIFS (SAMBA). Perhap the Qnap is just undersized. Are you about to log any storage or network performance metrics while your render is starting? Maybe you should be using 10gb ethernet. Ho big are the files being accessed?

All of this aside, on almost all NAS appliances, once the file is read, it stays in RAM until the caching mechanism expires the blocks due to time or just needing the space for new cache blocks. ZFS is a bit more intelligent with the use of ARC as a caching mechanism. Once a file is in cache the speed limit is usually the network.

 

[sretalla]

The benefit FreeNAS may offer would be ARC... the file can be served directly from memory if read multiple times (most server OS platforms do this, but FreeNAS is optimized for it... your QNAP may not have enough memory to keep all the files needed in RAM... make sure you consider this in designing a FreeNAS system... 8GB is the entry ticket anyway, but more is always better/recommended).

What you won't see is anything that will get around file locks... if your application locks the file for exclusive access, no server will help to eliminate that (perhaps the slowness you see is each client waiting for the next file it needs to become free/unlocked by the last client).

 

[kdragon75]

but FreeNAS is optimized for it

You mean ZFS.

perhaps the slowness you see is each client waiting for the next file it needs to become free/unlocked by the last client

Could be. I would think for render functions this softwares listed would be smart enough to not lock the file but he is using Adobe...

 

[sretalla]

You mean ZFS.

Well, since FreeNAS exclusively uses ZFS... FreeNAS is optimized for all the things that ZFS is...

 

[SourceVisualisation]

Thank you both for your replies; you've taught me some stuff already!

Not sure where you got this from.

An IT manager in a previous job used it as an explanation when I was accessing files from 20-30 PCs at once. There was a huge hang when accessing the files from a NAS but when we moved the files to their Windows server it was fine.

You don't mention HOW the files are accessed. Are you using CIFS, AFP, SFTP, or something else?

Please forgive my ignorance, but I don't know if it's any of those! I'm using Windows PCs to access the files via a wired LAN. Everything is wired through Gigabit switches.

Perhaps the Qnap is just undersized.

Almost certainly. It's the Qnap TS-419P II which has served me well for 6 years or so but I think it's time it was relegated to perhaps an off-site back-up drive. I'd just like to ensure I replace it with something fit for purpose, albeit with a limited budget.

Are you about to log any storage or network performance metrics while your render is starting? Maybe you should be using 10gb ethernet. Ho big are the files being accessed?

The files aren't often very big, generally no more than a few MB each. Just often quite a few at a time.

your QNAP may not have enough memory to keep all the files needed in RAM

That might well be the problem, I don't even know if it's got a GB!

perhaps the slowness you see is each client waiting for the next file it needs to become free/unlocked by the last client

I'd hope that the software would be intelligent enough for this not to be an issue, but yes, we're dealing with Adobe and Autodesk here - neither known for thinking things through properly when designing their software.

 

[Stux]

An IT manager in a previous job used it as an explanation when I was accessing files from 20-30 PCs at once. There was a huge hang when accessing the files from a NAS but when we moved the files to their Windows server it was fine.

There is a large range of devices in the NAS category, ranging from cheap and barely capable to heavy iron will run a Fortune 500 company

 

[Stux]

FWIW, depending on the size of your simultaneous active set, ZFS ARC and L2ARC could be a big win

 

[SourceVisualisation]

ZFS, from what I'm reading, does sound like it could be a good solution. So, let me be a little more specific, in the hope that I might draw from the wealth of experience on here.

What the NAS would need to be / do:
Purely a file server (no requirement for VMs or anything else as far as I'm aware).
Primarily storing project files and reference files for my business - this would need to have redundancy and decent speed
Secondarily storing family photos / videos / etc
Thirdly, as my office is at home, storing DVD and BluRay rips from which my media PC will read

The last point is one that's causing me some confusion. This is far from the main purpose of the NAS, but it's a very useful bonus since it's in the same building as my living room! We currently use Kodi (formerly XBMC) on a media PC as the front end, and it reads files from my Qnap NAS as well as its local HDD. Many people talk about running Plex on their NAS - would this be a benefit or could I just carry on the way I'm familiar with? If I understand it correctly, unless I'm running Plex or something on the NAS, the FreeNAS box would just be a file server, and therefore possibly an easier build?

What Raid configuration would be recommended for my use? My Qnap is currently using Raid5, which I felt at the time was the best balance between available space and redundancy against drive failure.

 

[bollar]

If I were in your situation, I'd want to confirm that your clients aren't outstripping your Qnap's ethernet bandwidth. Gigabit ethernet "feels" inadequate for numerous clients accessing many files at the same time. Perhaps there's an admin console on the Qnap that shows performance?

There are people here who can suggest specific hardware for every aspect of your build, but if it were me, I would look at a 5-6 drive system configured as RAIDZ2 (two drive redundancy). I'd also consider 10gigabit ethernet (which will also require upgrading your switch) and SSDs to ensure the system is as fast as possible when under load.

 

[sretalla]

SourceVisualisation[/URL]]The last point is one that's causing me some confusion. This is far from the main purpose of the NAS, but it's a very useful bonus since it's in the same building as my living room! We currently use Kodi (formerly XBMC) on a media PC as the front end, and it reads files from my Qnap NAS as well as its local HDD. Many people talk about running Plex on their NAS - would this be a benefit or could I just carry on the way I'm familiar with? If I understand it correctly, unless I'm running Plex or something on the NAS, the FreeNAS box would just be a file server, and therefore possibly an easier build?

One thing to understand is that Plex is a fork of XBMC (before KODI), which puts the media library management part into a server component (typically runs on your NAS/server box).

Since Plex has supported clients for almost all Operating systems (including tablets and smart TVs), it can enable you to get your content in a very ubiquitous way that works really well (including the scenario you mention ... you could also use the PleXBMC add-on in KODI... I haven't used it myself for years after happîly switching to Plex myself).

The potential gotcha is that in some conditions (usually device specific) the Plex server will want to transcode the file instead of streaming or direct-playing it on the client (usually where the client doesn't have/support the used codecs)... for that, you may want a completely different design on your NAS. If you're using a PC as your front-end, this should not happen a lot.

On the hardware side, I agree with bollar, RAIDZ2 is usually the good option... I would add RAM.... lots of it 16 or 32 GB if you can afford.

 

[SourceVisualisation]

OK, so if I understand it correctly I could continue doing what I'm doing without using Plex, and the NAS box is then just a file server? Bearing in mind the media hosting duties are far from the most important part of the box.

If that's the case, and I'm probably asking this in the wrong forum(!), but with my limited network understanding might I be better with a newer, faster off-the-shelf NAS box similar to my current one, rather than building my own FreeNAS system? I very much like the idea of building my own with hardware that will have enough headroom to do what I want, and I am keen to learn more as I go along, but might my money be better spent with a decent off-the-shelf solution?

 

[kdragon75]

might I be better with a newer, faster off-the-shelf NAS box similar to my current one, rather than building my own FreeNAS system?

If your data is important, build a FreeNAS based server. It's the easiest way to get into ZFS and ZFS keeps data safe. Most off the shelf boxes will choke under load. There built to be small quiet and cheap. Some rock, most don't. Non will keep you data as safe as ZFS. The means some over head and that's why people recommend a minimum of 16GB of RAM and a decent CPU (No old core2duo please).

For me to give any recommendations on hardware or configuration I would need real hard numbers. Number of clients accessing files at eh same time, size of files, how the files are written, total space desired, etc...

As for SSDs, unless you have all 10gb networking, you probably don't need them. You MAY want one for a SLOG (allows fast writes while doing synchronous IO) but an all SSD array is probably not cost effective.

On the networking subject, look at the qnat dashboard under Resource Monitor while your are starting your renders or anytime you experience slowdowns and make note of the LAN numbers. This will provide some insight on your network needs.