Quick hardware-related question

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dougoftheabaci

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I'm in the process of choosing the hardware for my first NAS and I've run into a question I don't know how to answer.

Basically, the case I've chosen supports six 3.5" hard drives and one SSD (I'm guessing it means 2.5"). That's fantastic as i can use the SSD for FreeNAS and then use the other bays for my data drives.

However, the best motherboard I can find for the job only has six SATA ports. I've found a PCI to SATA card that should work with my motherboard, but the reviewer says he was unable to install an OS onto a drive connected to it due to a lack of drivers.

He was using XP but I'm wondering if FreeNAS is going to suffer from the same problem? Also, is there another card or solution that would work better for my needs?

[EDIT:]
Another thought I just had, I'm trying to figure out how I'm going to install the OS on my NAS once it's built and one thing I was wondering is if it might be possible to drop the SSD into an HDD enclosure and install it from my desktop then drop it into the NAS with the driver already installed, if it's needed? I can grab a USB case for $20 and if that will solve the problem then it's money well spent in my mind.
 

jgreco

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Don't use the SSD for FreeNAS...! FreeNAS 8 is designed to run from flash. Find yourself a cheap 1GB USB flash drive.

Instead, use the SSD as a log device for ZFS (I haven't done this so I hope FreeNAS supports it) and then you don't need to worry about whether or not your BIOS will support booting from your random PCI-SATA card. You just need to make sure it's compatible with FreeBSD/FreeNAS.
 

dougoftheabaci

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Ah, so, basically, install FreeNAS on a thumb drive and then use the drives as I would otherwise. I'll look into maybe bringing in the SSD at a later date if I decide I want to improve performance but as it stands right now, I'm more wondering about the RAM issue that I saw in another thread.
 

jgreco

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What's the RAM issue you saw in another thread?

I can tell you with some certainty that RAM makes things more snappy. I've got these old AMD Opteron 240EE storage servers and going from 2GB to 8GB made things generally happier. I still can't turn on compression because of short periods of livelock, but it really cleared up most other issues with ZFS.
 

dougoftheabaci

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I saw in another thread that you were supposed to have 1 GB of RAM for every TB of HDD. I'm going to start with 4 GB of RAM initially but I'm eventually going to have six 2 TB HDDs in the box. By that measure I should have 12 GB of RAM? The max my motherboard supports is only 8 GB via two 4 GB RAM modules.

Or is that not how it's counted but rather TB of usable storage, in which case it would be 6–10 TB depending on my configuration? 6 TB if I mirror and 10 TB if I RAIDZ-1 (which I've been told is similar to RAID5 in that capacity is N-1).

Sorry, that brings me to another question. Should I be using RAIDZ or stripping + mirroring with ZFS? I've kind of been told both. I'm not looking for extreme performance beyond backups and the ability to stream HD content.

If that's actually a much more complicated question than it seems feel free to just say so and leave it for me to do more research.
 

jgreco

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There are lots of supposed rules, but the overriding one for FreeNAS 8 with ZFS is probably that you really want a bunch of RAM for ZFS. Based on ZFS experiences with things like FreeNAS and NexentaStor, I'd say that for smallish numbers of drives ("can count on hands"), you want a bare minimum of 4GB, 6GB is better, 8GB gets you nice and comfy. More is better but beyond 8 is probably diminishing returns; you win more on caching and the like. These numbers might need to be larger if we had de-dupe for ZFS, which we don't. :-(

From a service provider point of view, I had been waiting for FreeNAS 8 to transform some old Opteron 240EE storage servers into iSCSI and NFS servers; I wanted ZFS underlying. High performance wasn't the top consideration, and these things can only do about 50MB/sec NFS writes (to ZFS copies=2 over a routed network) but it does that at 85-90% idle.

RAIDZ has the one disadvantage that it makes a copy of everything. That might be good or it might be bad. It's simpler, certainly, but in our environment, it's better to make explicit decisions about those policies, so we're setting the machines up to stripe four disks, and then manually tuning zfs datasets for things like copies=2 (or =3 or whatever) where that's desired. Not all data is equally valuable. For a "home NAS" you're probably fine with RAIDZ.

RAIDZ has advantages and disadvantages, you get to read up on them though, as I don't have time to outline problems like mismatched drive sizes under RAIDZ or the impact of multiple copies if you go with striping. If you're not too freaked out about things like maximizing disk space or performance, you can't *truly* mess up whichever way you go.
 

dougoftheabaci

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Oh, I know about the miss-matched drive size problems as RAID5 seems to have a number of the same issues. However, I'm going with all 2 TB Samsung HDDs. Samsung because I already have one and it's solid like a rock which works fine for me. I don't need 7,200 RPM drives because aside from when I'm doing backups or moving files onto the device it's going to do very little beyond sleep and stream files to my computer or my roommate's PS3.

That's why I'm thinking RAIDZ might be just the ticket as it maximizes data storage for my needs. As for data redundancy, I'm happy to let it back up everything equally with two copies. The whole reason I'm doing this is because I want my data 100% protected as much as I can from a device that's sitting in my apartment and doesn't cost me multiple thousands of dollars. I originally decided on ZFS over RAID because of all the little problems RAID can have that ZFS is designed specifically to combat. After looking at how much it would cost me to buy the enclosures and a FW800 hub I decided it might be cheaper to build my own NAS. Turns out around $200 cheaper. It'll actually cost more to buy the 5 HDDs I'll need to fill the case than it will for all the parts I need for the box.

One thing I'm trying to figure out is whether I can just plug my NAS directly into my iMac via ethernet and running it like that rather than having it sit on the network. The reason being if it sits on the network it's going to be in another room and I'll have to access it via WiFi. Not really a problem except that it'll be slower.
 

jgreco

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One thing I'm trying to figure out is whether I can just plug my NAS directly into my iMac via ethernet and running it like that rather than having it sit on the network. The reason being if it sits on the network it's going to be in another room and I'll have to access it via WiFi. Not really a problem except that it'll be slower.

"rather than having it sit on the network" ...

If you plug two devices together with ethernet, you have a network. By definition. If you mean "rather than having it sit on my other network", that's slightly more complicated. If the iMac is connecting to your other network via WiFi (presumably for Internet etc), then it may have a free ethernet port. By connecting a FreeNAS box to the iMac, you gain a second network - but one that is (at least by default) only reachable from the iMac. What makes the most sense is largely a matter of what you're trying to accomplish. If the iMac is the sole consumer, then that probably makes sense. If you specifically need very high speed access from the iMac, it probably also makes sense. If you're just using the FreeNAS as secondary storage and it'd be handier to be able to access it from other networked devices, then you might want to reconsider.

The great thing about ethernet, though, is that you can always unplug it and plug it in somewhere else.
 

dougoftheabaci

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Yeah, the semantics of how I put it does seem a bit off. However, there maybe a way to still share the device through my iMac but that is definitely of secondary concern.

One of the reasons I'm going NAS over something like FW cases and so forth is because Time Machine doesn't support ZFS volumes. It does, however, support NAS shared via AFP so I'd be able to use one box as my file server, backup server, media server and local web testing server. I've been looking around and all of these things seem to be doable with FreeNAS. What I'll likely do is attach my NAS via ethernet to my iMac for the initial data transfer and backup (there is so much to put on it...) and then move it onto the router as while initially it's really only going to be accessed by my iMac, it'd be nice to be able to access it via other devices as becomes necessary.

Mostly, I like the power and flexibility of an NAS.

To be honest, the only problem I have yet to figure out is how I'm going to install it when I don't have a monitor, keyboard or mouse I can use. I'm likely going to have to see if I can borrow them from someone. Unless there's a way for me to pre-configure it so that once I plug in the thumb drive it's pretty much ready to go. Gotta look into that...
 
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