It works for me but it's not supposed to?

[el-John-o]

Hey all,

So I went through the FreeNAS manual and reconfigured my Ubuntu server box to run FreeNAS. Now I read the vague '8GB is typically the minimum' and 'below 4GB prefetching is disabled' parts, so I figured my 2GB system is in the clear with reduced performance and features. No biggie.

But then I came on the forums and found out that, running ZFS with less than 8GB of RAM is completely ill advised regardless?

I have a single Xeon 2.8GHz (single core, dual socket but only one CPU in) server with 2GB of DDR2 RAM, running (currently) a 1TB mirrored ZFS pool. It's all SATA 1.5Gb/s.

I'm getting 110-115MByte/s read speeds and close to 50MByte/s write speeds. So performance is, basically, saturating gigabit. So the other issue I read, is that when transferring large files, you can get errors or kernel panics. Well, I 'backed up' my RAID before setting up FreeNAS, and copied back some 300GB of data, with lots and lots of 2, 3, 4 even 7 or 8GB single files. It ran at a constant throughput speed of about 58MByte/s, and never had any issues.

So I guess my question is.. what's the issue? I look at a machine that runs quite well, should I expect problems in the future or something? DDR2 is pricey, so I'm not going to upgrade this machine. I plan on building something new in the future, so spending any money on this box just doesn't make sense. I guess I could back everything up and rebuilt the pool as a UFS setup, but I'm failing to see why? I don't have any issues.

I have FreeNAS configured pretty much vanilla, and I'm running a CIFS share to my Windows box, and an NFS share to my linux and Mac boxes. The NFS share is the fastest, the CIFS share is a bit slower but still quick..

 

[JaimieV]

No, there's too much fuss made about memory sizing. For a domestic NAS that will only have one or two streams coming from it at any time, 2gig might be a bit small but will work okay under almost all circumstances. Don't expect to do anything fancy (and memory hungry) like running jails though. Compression is fine, but don't dedupe!

I run my backup NAS (4Tb of disks) with 1gig, because it came with that and it hasn't had any trouble. It only ever has one stream - the backup from the main NAS, which has 8Tb (not full!) and 5gig RAM. No jails. Again, no issues.

For a workgroup NAS with a dozen or more people attached to it, go with the recommended memory for sure. For home, nah.

If you do have issues, don't be surprised if people look askance at the low memory situation though, and suggest banging another 4gig in or something.

 

[el-John-o]

No, there's too much fuss made about memory sizing. For a domestic NAS that will only have one or two streams coming from it at any time, 2gig might be a bit small but will work okay under almost all circumstances. Don't expect to do anything fancy (and memory hungry) like running jails though. Compression is fine, but don't dedupe!

I run my backup NAS (4Tb of disks) with 1gig, because it came with that and it hasn't had any trouble. It only ever has one stream - the backup from the main NAS, which has 8Tb (not full!) and 5gig RAM. No jails. Again, no issues.

For a workgroup NAS with a dozen or more people attached to it, go with the recommended memory for sure. For home, nah.

If you do have issues, don't be surprised if people look askance at the low memory situation though, and suggest banging another 4gig in or something.

That makes sense, I was just curious.

I read the manual and got the impression that performance was best with more, but it would work with less. Well, it's an IBM server from 2004, so, if performance was that big of a concern I'd be buying something new!

But, like I said, I hop on the forums and all of these threads say it won't WORK with ZFS and less than 8 gigs of RAM. But I have 2 gigs and I'm saturating gigabit with consumer drives.

I'm thinking about adding a PCI-X SATA controller. I have a nice Intel hardware RAID controller, but it doesn't support more than 1TB drives. I'd like to eventually build the array in RAIDZ with 4 2TB drives in the nice hot-swap bays, and an SSD for cache. Just trying to decide if it's worth doing in this machine or not. It IS upgradable to 16GB of RAM, but DDR2 is very expensive.