Hi,

Although the subject pretty accurately describes the question, I will start with a bit of background:

Problem

I currently have a QNAP TS-209Pro with 2 750Gbyte Seagate 7200.10 drives in RAID-1 operation. The thing works well, but:

* Both its Samba daemon and NFS deamon are CPU bound at ~20 Mbyte/second, even when using 9 kbyte Jumbo frames on the Gbit interface. It's 500 MHz CPU is just to slow, and it does software RAID.
* Since the system boots from the data drives, running something as simple as a Tor node or other service will keep the drives spinning.

Requirements

I would like a system that is:

* As low-power as possible.
* Fast when it needs to be (preferably I/O-bound on the HDD transfer speed, so some 40-60 Mbyte/s).
* Quiet when it is not used (see SSD remark below)

Usage pattern:
* Idle but on 24/7, running a few % CPU on services like Tor.
* Used 1 hour per day for heavy duty.
* Just a server; no display, no keyboard/mouse, no sound.

Proposal

Given the low-power requirement, I started looking into Via Eden CPUs, and I found a solution that seems very attractive: A VIA EPIA EN12000EG
board, which holds an Eden 1.2Ghz CPU with low (<12W) TDP. This thing would be in a small case with a small SSD that holds the OS.

Since it proved hard to find a reasonable mini-ITX case that holds two drives, I decided to look to external RAID enclosures. I found the following rather interesting box: a RaidSonic SR3620-2S-SB2 (URL not allowed; I'll post that later), which has external eSata connectivity and does hardware RAID 1 (i.e., from the OS point of view).

The idea would be to have my data drives (2 x ~1 TB, in RAID1) in the external box. The small case would then house just the VIA board, a small SSD, and a GByte of RAM.

Questions

* Does anyone have experience w/ the Eden 1.2GHz CPU? Does it have the oomph to process 60 MByte/s SMB or NFS traffic?
* How transparent is eSata? I.e., is it possible for the OS on the small box to tell the eSata box to spin down its drives when they are not in use?


Thanks very much in advance for sharing any info!

Niek

As promised: the URL for the RaidSonic:

http://www.raidsonic.de/en/pages/products/soho-raid.php?we_objectID=5049#techdata

For what it's worth, I recently built a small FreeNAS server using an old 1.2GHz Pentium III box - transferring big video files via FTP, it maxed out at 25-26 MB/sec, with 100% CPU usage according to the FreeNAS GUI resources monitor. Another FreeNAS server on the same network, using a 2.6GHz Celeron, could manage around 45-50MB/sec via FTP, with CPU usage of around 30% (it seems the bottleneck was elsewhere in this system, probably the HDDs themselves).

CIFS/Samba transfers were much slower in each case, presumably due to FreeNAS/BSD's crappy implementation of the protocol.

So I rather doubt you'd ever see 60MB/sec using a 1.2GHz Eden; in fact, I think you'd be lucky to get even half that...

Wouldn't a newer chipset be offloading more off the CPU though? A P3 would obviously be running on a more basic chipset. Also slower ATA on the old P3 board? Not that this helps with the question, hopefully someone with experience with one of these boards will chime in.

I doubt if the IDE interfaces (ATA/100) would have been a limiting factor - even ATA/66 gives you 66.6 MB/sec.

I think you're right about the CPU offloading feature though, at least according to the specs for the VT6122 GigE controller used in the EN12000EG. I guess it would need somone who actually owns one to report on how well it works in practice.

Well, I'm not really sure how you define 'resonable', but there are a couple of NAS sized mini-itx cases you could probably use:

http://www.logicsupply.com/categories/cases/mini_itx

The first couple on that page are mini-itx cases with either 2 or 4 hot swappable sata holders. No idea how quiet they are, though. And I suppose they might be a little pricey. Logic Supply also has a fairly wide selection of mini-itx boards, including this one:

http://www.logicsupply.com/products/sn18000g

which is a 1.8Ghz via c7 board, but the big plus is that it has support for 4 sata drives, which is fairly unique. Most of the other boards have support for 2 sata drives, so there are plenty of choices there, including a new via Nano board, and also some Atom boards too. I'm not sure how well they all work relative to each other, but the Eden is getting kind of old, I'm sure newer processors would perform better. But anyway, just thought I'd bring this stuff up, you can evaluate against what you really need for your application, I suppose.

Typically, you are limited by these things:

1. CPU speed
2. NIC CPU offload features & driver quality

From experience, like nick705 suggests, I'd guess that you'll probably only be able to push up to 30MB/s.

Also important to know is the architecture of the motherboard. Hopefully the NIC and the SATA/IDE controllers are on a PCI-E bus - if they are on a PCI bus they could be sharing 133MB/s meaning the fastest you'll see streaming data from disk over the network would be ~65MB/s.

That said - I suspect that the system would do well for you most of the time. However, for a fraction of the cost, you could build an inexpensive Athlon LE-1640 or similar system that should have very low idle power with the right motherboard, memory and disks.

The Via SN looks an interesting option, more info on the Logic Supply blog with some useful feedback from users. A problem may be chassis compatibility, due to the CF and mini-PCI on the underside of the board...

Another option is the IEI KINO-690S1... with a low-end Sempron you'd get low power but still good enough performance. Seen some coming up on eBay recently at good prices...

eSATA should be 100% transparent; it's basically an internal SATA connection with a different cable.

I've been running OS X off an external eSATA drive for about a year without problems. The system has no idea the drive is external.

Raidsonic RAID1 box would probably be quite a tight bottleneck -- solutions like this tend to be very slow, even doing simple stuff like raid1. far from 40-60MByte/s, anyway.


I also would not recomment Via SN boards (ain't got any experience with the EN series, though) for this task. I've got an SN10000EG powering a small server (debian gnu/linux, unstable tree, custom-built 2.6.28 kernel, one 2.5" system drive and a couple of 1TB EcoGreens in an md raid1 array, using XFS, write-cache is disabled on the EcoGreens). There's a bunch of serious issues with this board:

- the AHCI implementation of the SATA-controller is seriously flawed. using NCQ in AHCI mode can lead to controller lockups. thus, no NCQ in AHCI mode.
- I wasn't able to use any of the cpu-offloading features of the gigabit controller. setting MTU to any value above 1500 makes the NIC stop transmitting packets after a short while (immediately with a kernel before 2.6.26, AFAIR). could be an issue with the via-velocity driver in the linux kernel -- I gave up trying after a while, so I'm not quite sure -- NFS or CIFS performance is not that important to me. NFS throughput while reading large files max out at ~25Mbyte/sec after some tweaking, CPU load at ~20-30% maximum.
- it definitely does cost too much to have such serious flaws

on the other hand, it has some nice features, like redirecting bios/bootloader console output to a serial port, small size, and a 16x PCIe slot, which should also accept some really nice Intel 1x PCIe Gbe card, solving the second issue. The AES/SHA-accelerator also works nicely, improving perfomance on encrypted volumes.


...and subtly different electrical specifications. should not be a problem with most hardware, though. sorry for nitpicking