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wilburpan · Mar 26, 2007, 09:28 AM

I have a old 750 MHz Pentium III computer that I've turned into a Linux fileserver. My thought was to transfer my photos and music files over, and set up iPhoto and iTunes to manage the library off the fileserver. It does work, but the performance of iTunes and iPhoto seems to have taken a hit.

I have my iMac and the fileserver hardwired into my network, so it's not a wireless speed issue. However, I don't know exactly where the bottleneck is. It could be the slow Pentium III, or it could be just inherent to running iTunes/iPhoto off of a networked drive.

My question is, would a faster processor in the fileserver speed up performance, or is the performance hit inherent to running iPhoto or iTunes off of anything but a local hard drive?

Big Mac · Mar 26, 2007, 09:52 AM

It's most likely hard drive speed.

wilburpan · Mar 26, 2007, 12:35 PM

In my case it's probably not the hard drive. Although the computer is old, the hard drive is new, and is at least as fast as the hard drive in my iMac.

spice003 · Mar 26, 2007, 03:39 PM

upgrade to faster/ more ram, and switch to gigabit .

Tomchu · Mar 26, 2007, 03:58 PM

Upgrading to "faster" RAM isn't going to do a damned thing.

Run a network benchmark (like iperf) to see what kind of transfer rates you get between your Mac and the Linux box. Over a decent 100 Mbit network, I get about 11.5 MB/s, so you should be aiming for about that.

You should note that that is still less than half the speed you'd get from even a laptop hard drive on the local machine, so the suggestion to move to Gigabit (if you aren't already on it) would probably do more for you than upgrading the CPU or RAM or whatever else in the server.

Also, try using NFS if you aren't already. SMB has high overhead.

ghporter · Mar 26, 2007, 05:11 PM

Hard drive speed, followed by controller speed, followed by bus speed are the top three limiting factors for you. The 750MHz P III should be just fine for serving up files, but you need to understand that it has to ask for the data, get the data, and then push it out the network card. So if the drive is up to the task, what controller are you using? If it's a motherboard controller, get a fast PCI ATI controller card. If you have a fast card (as in ATA 100 or better), then the computer's bus speed is impacting you. Can't do much about that without replacing the computer...

A newer network card would help some too, since they do get better over time-especially driver support, which can be crucial.

wilburpan · Mar 26, 2007, 07:16 PM

Originally Posted by Tomchu

Upgrading to "faster" RAM isn't going to do a damned thing.

Run a network benchmark (like iperf) to see what kind of transfer rates you get between your Mac and the Linux box. Over a decent 100 Mbit network, I get about 11.5 MB/s, so you should be aiming for about that.

You should note that that is still less than half the speed you'd get from even a laptop hard drive on the local machine, so the suggestion to move to Gigabit (if you aren't already on it) would probably do more for you than upgrading the CPU or RAM or whatever else in the server.

Also, try using NFS if you aren't already. SMB has high overhead.

Thanks for the iperf tip. Running iperf in server mode on my Linux box and client mode on my iMac I'm getting 16.6 Mbits/sec. I am using afp on my Linux box, by the way, not Samba.

It looks like Gigabit might be the answer, but I don't think there is a way to upgrade a G4 iMac to Gigabit Ethernet. Just out of curiosity, how does hard drive read/write speeds compare to Gigabit Ethernet?

besson3c · Mar 26, 2007, 07:23 PM

AFP is your bottleneck, it is slow as hell - whether you are running Netatalk or the native AFP off of OS X.

You should *definitely* try something else before you make any drastic changes. My recommendation would be to use SSHfs/FUSE.

Appletalk blows.

besson3c · 07:37 PM

You do *not* need gigabit (or, at least, I'd be surprised if you did), you are probably not saturating your 100 base-T network, you are just dealing with a protocol level obstacle.

If you decide to look into SSHfs, I've written a guide you can access here:

NetMusician Labs � Blog Archive � FUSE and sshfs in OS X

NFS is also a viable option if security is not an issue.

Tomchu · Mar 26, 2007, 08:17 PM

Originally Posted by ghporter

Hard drive speed, followed by controller speed, followed by bus speed are the top three limiting factors for you.

Err, not if he's on 100 Mbit. Even a PIO Mode 4 hard drive (~16 MB/s) can saturate a 100 Mbit line.

Originally Posted by wilburpan

Thanks for the iperf tip. Running iperf in server mode on my Linux box and client mode on my iMac I'm getting 16.6 Mbits/sec. I am using afp on my Linux box, by the way, not Samba.

You sure that's 16.6 Mbits/sec? ;-) My number in megaBYTES per second is 92 megaBITS per second, which is close to the maximum theoretical speed of 100 Mbit Ethernet. If your 100 Mbit line is pulling only 16.6 Mbits/sec (just over 2 MB/sec), then I would figure out what's causing that slowness.

Originally Posted by wilburpan

It looks like Gigabit might be the answer, but I don't think there is a way to upgrade a G4 iMac to Gigabit Ethernet. Just out of curiosity, how does hard drive read/write speeds compare to Gigabit Ethernet?

Well, I can do a sustained 107 MB/s between my Core Duo Mac Mini and MacBook Pro, going through two Gigabit switches (that's about 856 Mbits/sec, or 85.6% of the maximum theoretical speed of 1000 Mbit Ethernet). I believe that the average sustained transfer rate of my MacBook Pro's hard drive is about 25-30 MB/s -- so less than a third of what Gigabit can do, but almost three times what 100 Mbit Ethernet can do.

ghporter · Mar 26, 2007, 10:09 PM

Originally Posted by Tomchu

Err, not if he's on 100 Mbit. Even a PIO Mode 4 hard drive (~16 MB/s) can saturate a 100 Mbit line.

It can if the controller is efficient. With this situation and not knowing if he's talking about an old ATA33 controller on the motherboard or not, having more efficient access to the drive could help. Sure, pure, all out PIO Mode 4 can saturate a 100Mb/s line, but only if all of that PIO data gets straight to the network card without any choke points. In my experience it helps to have a good controller as well as a good drive as a first step toward higher throughput.

And there is the P III computer's bus speed to deal with. Some older motherboard ATA controllers, even in the P III era, show up as ISA devices, not PCI, and that could be a major slower right there.

No contest that a decent PIO-4 controller and good drive would be more than enough, but getting the two together is not necessarily easy with some nebulous "750MHz P III" computer, thus my suggestions.