More than 4 GB RAM

[doglover]

Hello. I have just set up a core2 duo and 4 GB RAM with 3 1.5TB drives in ZFS raidZ-1. I have read many posts about how 4GB is not enough. I hesitate to spend more since it is just me using the server lightly so far (ok, maybe wife also but very rarely). Also, when I look at the RAM usage, it has really never gone over 1GB used since I have had the machine up for a few days. Not clear why I need to spend for more when it isn't using what it has.
Thoughts please? I don't want to lose my data in the future.

Thanks,
IMF

 

[cyberjock]

My understanding is that anything "free" is not "free", its filled with cache data. If a program suddenly needs more RAM then the cache is supposed to shrink. However, sometimes things go wrong and the kernel panics when it can't get the RAM it needs. Some people have no problems for months, then they can't get their server to stay up for 24 hours.

The manual says you should have 6GB for ZFS. I promise you that if you come in this forum and complain about a kernel panic and/or slow performance you can expect someone to tell you to RTFM for not using 6GB.

 

[jrdbrr]

What are you using the NAS for? I'm using it to watch videos on my xbox - running on a p4 with 3gigs of ram and no problems- not even close to maxing out the specs.

 

[doglover]

Hi all. Thanks for the comments. Before I run out and spend over $100 for more RAM (already have 4gb), I wanted to explore the idea of UFS Raid3. I searched the forum here and found only two hits on Raid3, and didn't do much better on Google. I am pretty much a single user with fairly light requirements. Sure I want it to be fast if I push over an iso or stream a video, but won't be doing that very often. I plan on keeping a good backup. So if I go with UFS Raid3, will I really notice the difference and can I keep my money? Anyone out there happy with UFS Raid3? If I have a good backup, do I need Raid at all? Thanks for the comments. With respect,
IMF

 

[warri]

Why not stick to ZFS Raid-Z? You don't seem to have problems so far, and only plan light usage. Many such systems run totally fine with 4 GB.

 

[Z300M]

What memory are you using that's going to cost over $100? I just bought a pair of 4GB DDR3 sticks from NewEgg for US$30.

 

[doglover]

Hi Warri. Please see response #2 above. There are other similar sentiments out there that suggest bad things might happen. And of course there are those which suggest, like you, that I will be just fine. Wish I knew who was right... I want to pick a setup, go with it, stick with it, and not look back. That is why I was trying to see if people out there were using UFS-Raid3 with 4 GB RAM and were happy. Near as I can tell, there are not many.

 

[doglover]

Hi Z300M. Yes, DDR3 is now cheaper than DDR2. The best sale price I could find was approx $25 for a 2GB DDR2 stick on sale locally.

 

[warri]

As you can see I'm running a low-end ZFS system (Atom, 4GB RAM) and my system is running stable for almost one and a half year now. Usually there are 2-3 local users + some with remote access. Never encountered a kernel panic, the system just slows down on concurrent access. My mainboard takes DDR2, that is why I hesitated to upgrade as well - but also there was no need to upgrade since everything runs smooth and stable.
So if you really just plan to have 1-2 local users, don't waste your money now. You can still upgrade your system later on, if you encounter any problems or want to expand it. (+ in the future you can probably use DDR3 RAM and other modern components. You won't really be able to use the DDR2's in any new system..)

 

[cyberjock]

If I had a system with only 4GB of RAM and it worked fine and I was happy with the performance I'd just leave it alone. Don't touch it if it isn't broken. But if you start having performance or reliability problems and you didn't have a clear indicator of something specifically broken I'd blame the low RAM and upgrade that first.

You may get lucky and never need more than 4GB. But I also agree with the other people, I'm not sure where you are getting $100 for more RAM at. Atoms are all DDR3 to my knowledge and DDR3 is cheap. 4GB sticks are $25 or so.

 

[jgreco]

FreeBSD runs ZFS fine on 1GB or less, but some tuning may be necessary. FreeNAS hasn't really bothered with the tuning, because it adds complexity to an already difficult thing they're trying to do, so it's better for them to focus on just giving a number that's expected to work. That doesn't mean it can't or won't work with less, and it means that anyone who does some minimal reading on ZFS and FreeBSD and tuning can get a handle on the basics in about 10 minutes.

The forums are littered with the .sigs of people running smaller memory systems without incident.

 

[doglover]

Hi Noobsauce80. Please see post #1. I have the core 2 duo. Warri is the one with the atom. I would love to wrong on this and fine cheaper prices but checked on NewEgg like suggested and still can't find 2GB PC6400 800 DDR2 for much under $25. So, 8GB will cost over $100 after tax or shipping. Anyhow, I will keep looking, limp along with 4GB, and hopefully not lose any data. Thanks all! Interesting that so few responded using UFS.
Cheers, IMF

 

[doglover]

Hi Jgreco.. I did try yesterday reading about ZFS tuning but at the moment it is a bit over my head. I will keep trying but I may have to stick with the defaults for now until I can grasp it better.
Thanks IMF

 

[cyberjock]

Interesting that so few responded using UFS.

Well, when it comes to data reliability UFS doesn't have a candle to ZFS. In fact, there's nothing out there that even remotely competes with ZFS.

 

[jgreco]

Well, when it comes to data reliability UFS doesn't have a candle to ZFS. In fact, there's nothing out there that even remotely competes with ZFS.

Oh, that's a bit overboard. Yes, ZFS has some great new features. However, you make it sound like storing data with UFS is a recipe for disaster, when it isn't. The fact of the matter is that people have been storing data with FFS/UFS for decades and it is a trusted system. ZFS has features specifically to address data reliability, and FFS lacks them. ZFS will (by default) checksum your data and make sure it's read back correctly. ZFS will recover data if possible if the storage is redundant. ZFS can periodically scrub for errors. Those ARE nice features. However, ZFS also adds complexity to the storage system. How many times have we seen someone here crying about their lost pool? I just don't see a lot of that happening with FFS... because it doesn't attempt the massive scale multi-disk all-reaching goals of ZFS.

Put another way, ZFS has the potential to fail big. I would definitely want to consider that when judging ZFS's data reliability. Sure, ZFS can protect you from a failed hard drive. However, it makes the possibility of an administrator's error substantially greater. Just another factor to consider.

 

[cyberjock]

However, you make it sound like storing data with UFS is a recipe for disaster, when it isn't.

I'm just saying that ZFS has alot if data reliability features built in that no other file system anywhere shares. It's very unique in this and while it may be the most reliable file system ever created there are obvious benefits and detractors. YMMV and you should definitely do your homework.

However, ZFS also adds complexity to the storage system. How many times have we seen someone here crying about their lost pool? I just don't see a lot of that happening with FFS... because it doesn't attempt the massive scale multi-disk all-reaching goals of ZFS.

But also how many people are using FFS? It seems like the vast majority are using ZFS. Even doglover commented at how few people have mentioned using UFS.

I'm also not sure if I can blame user error for being ZFS's fault. It's not like those limitations aren't well documents in the ZFS documentation, in the FreeNAS manual, in my guide, all over the forums. If you don't do your homework you can be very disappointed. What about those people that choose to use FAT32 then cry when they can't put an 8GB ISO on the partition because the file system is limited 4GB? That's user error too, but that's not FAT32's fault. That's an incompetent administrator.

 

[jgreco]

Almost nobody uses UFS in FreeNAS because the purpose of FreeNAS is to manage network storage, and usually the people smart enough to want this are looking for the features. But some of us have done FFS. It fits certain use models.

Almost nobody uses ZFS in FreeBSD because it's still regarded as somewhat experimental, slow, and piggy. I think they finally worked around some of the "really annoying to install" issues.

Now, 99% of FreeBSD-derived installs are FreeBSD, not FreeNAS, so from my point of view, the FFS/UFS installed base is effin' gigantic compared to ZFS. The FFS in FreeNAS is no different than the FFS in FreeBSD, so for the purposes of this discussion, what I see are millions of filesystems that've successfully stored files over the last two decades, while ZFS's track record is more ... um, recent, is that a polite term? (did someone actually suggest ZFS could cause a kernel panic just a few messages back?)

The point is that it's probably a little unfair to place such emphasis on data reliability features. It is kind of like me saying my vehicle is safer in a car crash. If that's because I'm running around in a Hummer, it fails to recognize that I'm probably going to kill the other guy, and that I'm making a much larger environmental impact with pollution. For the most part, people losing bits in a way that ZFS would catch but UFS would not is a very unusual event. On the flip side, ZFS tends to make storage systems more complex and therefore more breakable. Sure, you can blame the user, and that might even be fair in many cases, but lost bits are lost bits... there's a little bit of irony in a system with such great data reliability features being able to lose bits more easily.

 

[doglover]

Two things.
1) My first question was really about UFS Raid3, and I have heard nothing about that.
2) Forget question #1, since I caved, went out, spent the $105, and bought the 8 GB. Running memtest on it now. Now hopefully I am done, don't have to worry about the future, can expand, and never look back.
Thanks all for the help, with respect,
IMF