BUILD Appropriate Build for iSCSI and Plex

[Fluffybonkers]

Hello all,

First post on the forum but I have spent much time lurking and reading up about ZFS. Thus, I wanted to run my current plans by the experts before embarking on the complexities of implementing everything.

Firstly, I plan to use this as a home server for Plex (max four streams with limited transcoding), Squid (proxy server), block-based iSCSI (more on this later), OpenVPN, router and firewall, and standard SMB/AFP/NFS file sharing. I will not be running VMs of any sort. I will actually be using ZoL just because I am more comfortable with Linux, but I respect the knowledge of ZFS here and am thus asking on the FreeNAS forum. I am in Australia and so the most of the sites I link to are with Australian prices, the Newegg ones I link to are what I plan to pick up on an upcoming trip to the U.S.

The hardware:

Case: Fractal Define R4

Motherboard: Supermicro MBD-X10SLM+-F-O

Ram: Crucial 16Gb kit x2 (recommended on the forums and yes, with ECC!)

CPU: Intel Core i3 4160

Hard drives: 4x Seagate SV35 3tb (raid 10 or raidz2, more on this)

Backup drives: 2x 3tb external usb 3.0 drives. Nothing special. More on this.

PSU: Seasonic G series 65ow (I can't afford a redundant one right now, but I am interested to know whether a redundant PSU would help prevent other components been taken out when the PSU fails. This is the only thing that is important to me, not uptime.)

UPS: Undecided on this. I currently own a 390w Cyberpower one, however I am unsure if this will be sufficient.

There are a few things I am worried about with all this.

I am aware of how easy it is to run into performance issues with iSCSI but what I am unsure about it the degree of the problems. I am planning to run two windows desktops with all their data off two iSCSI shares (with two associated zvols). The only thing not on the shares will be windows itself (can't be bothered going diskless). The desktops are used for browsing, standard office productivity and gaming. All applications will be running off the shares. Most of this stuff, once loaded, goes into ram, so in some respects, iSCSI performance isn't a huge issue i.e. I would be happy with 100MB/s on large, contiguous files. However, if I am hitting 10MB/s, that would be an issue. I have tried to spec the ram on the server appropriately as per other posts on this forum, but I am aware Cyberjock feels that you don't get serious performance from iSCSI until >32gb, potentially also with L2ARC. I can't do this and as I said, it is about the degree of performance hit.

Secondly, I am unsure about the specifics of raid 10 vs raidz2 performance. Obviously raidz2 offers better redundancy, but with decreased performance. If the feeling is that I will still get reasonable performance i.e. >=100MB/s for large contiguous file transfers e.g. movies rips, I am fine with that. If not, I will take the risk and go with Raid 10. I have calculated risk of failure with Raid10 here using MTTDL methodology and, while greater than raidz2, it is still low. I can expand on the settings and figures I used in the calculator if people are interested, but for Raid10 I arrived at 0.0417724169533384 over five years, and for raid6/raidz2, 0.0000294092546129. That is a significant difference, but relatively speaking, 4% is still low enough for me to feel comfortable. I also used conservative figures. There are problems with this methodology discussed here that people can read about if interested. I am unsure how people feel about it on the forum.

Thirdly, I plan to backup files that are directly on ZFS to one external 3tb usb 3.0 drives (formatted as Ext4, Linux OS images will also be stored here), and the Windows clients will backup the files stored on iSCSI to the other shared, NTFS formatted external drive. What do people think about this?

Thirdly, I don't really understand the impact of catastrophic OS failure on a ZFS volume. Obviously FreeNAS is mostly run off a USB and loaded into ram after boot, but I can't do this with Linux. My current plan is to run the OS off a standard, old, 250gb Ext4 drive. However, if the drive fails and this will in some way impact my ZFS volume, I could potentially do Raid1 through MDADM with 2x 250gb OS drives. If an OS drive dying won't take my ZFS volume with it, I don't care if the server is offline for a little bit while I setup the OS again.

Lastly, I am sorry for the long post but I have tried to provide as much information as possible and avoid the "stupid noobie question" syndrome that pervades this forum e.g. continuing ECC debate. I have read your presentation Cyberjock! If I have missed anything super important, I will try to provide it.

Thanks for any advice,

Fluffy

 

[cyberjock]

Mirrors don't always result in decreased performance. In fact, they almost guarantee far superior performance for the same number of disks. ;)

To be honest, this place is a good primer for ZFS for FreeBSD, but I would NOT take this information as being completely accurate for Linux. The same has been noted (and documented) to be true for other implementations. So unfortunately all the homework you are doing for ZoL isn't really doing you much good. :(

 

[Fluffybonkers]

Thanks for getting back Cyberjock. I am aware there are documented differences and thanks for warning me, it is just that ZoL lacks the same kind of dedicated forums, making it harder to find information. Also, surely things like the iSCSI/RAM debate still hold true, since, while it is a different OS, it is the same filesystem. Sure, different kernels, different iSCSI implementations, but I think there must be some crossover. Either way, for the sake of argument, what do you think of this build for FreeBSD/FreeNAS? I have used FreeBSD before, but by no means am I an expert.

 

[cyberjock]

The build itself seems solid.

Yes, there is definitely crossover. The problem is unless you can actually identify *what* that crossover is you should assume nothing is similar. Unfortunately if you are skilled enough to identify what in particular is the same and different you wouldn't have to come to a forum for answers.

That being said, I'd expect that the hardware would work on Linux and be fine, but I am by no means the person that should be relied on for using the hardware on Linux.

 

[Fluffybonkers]

Thanks for getting back. Considering the lack of guides on ZoL and potential performance problems, worse than any that might exist on FreeNAS/FreeBSD, I might just bite the bullet and go the BSD route. It can run everything I want it to, it is just a matter of acquainting myself with a new OS.

 

[cyberjock]

You can always try Linux and if it flops go to FreeNAS.

Not that I'm trying to dissuade you from using FreeNAS...