Re: Digital switch over query

The message <1238442633_5231@xxxxx>
from J G Miller <miller@xxxxxxxx> contains these words:

On Mon, 30 Mar 2009 16:28:51 +0100, Johnny B Good wrote:

> As long as we don't tempt fate by naming any servers "Heisenberg" ;-)

I wonder if anybody has named theirs "Titanic"?

> Just the boot device, as far as I could tell.

So the mother board BIOS fully supports booting off a USB device presumably.

Indeed, that is correct.

> Excuse me, but the FreeNAS installer _isn't_ intended for just one
> specific hardware setup.

Okay, I misunderstood -- I thought when you were talking about a NAS
device you had something like a QNAP or Buffalo station or whatever.

Oh no. I wouldn't waste money on an overpriced bit of kit that could so
easily underperform even worse than my earlier Gbit NAS setups.

In fact you just have a "regular" PC with disks.

Effectively, that's right (except that the latest MoBo was chosen on
the basis of having a built in Gbit lan port _and_ four SATA ports).
It's not my fault that this four disk NAS box built into an almost
silent secondhand Gateway 2000 desktop case uses less power than that
Atom based test project. ;-)

For such a set up, you could actually use any GNU/Linux distribution,
and buy careful configuration easily set it up as a NAS server, along
with web, DNS etc.

Yeah, I know. That was my first alternative to the Netware 3.12
fileserver I'd previously been using. The thing is, that was set up with
a Debian based server by my daughter's boyfriend with a webmin style
interface installed (perhaps an early evolution of webmin itself - it
was quite a few years ago). Apart from using the webgui tool, I left it
well alone until I decided I'd had enough of the lousy 6.8MB/s wire
speed limit with 100Mbps ethernet and felt it was time to upgrade to
Gbit ethernet.

I soon discovered that Gbit ethernet required a lot more of an upgrade
than just dropping a GA311 card into the socket7 MoBo and landed up
using my spare V600DAP board with a vastly underclocked/ undervolted
Athlon XP2500+ cpu by which time, the original Debian install was
'broken'. That's when I tried the FreeNAS alternative amongst others
(such as the ClarkConnect NAS server) which were free software. I'm
pretty certain I tried a third contender, but I can't recall what it was
off the top of my head right now.

In my case, I have a Linksys NSLU2 with two Philips 500 GB disks running
Debian Etch as a network server.

I've just googled my way to a wikipedia article on the NSLU2. I'm
afraid its lack of Gbit connectivity and two drive limit puts it well
out of contention as far as I'm concerned. Have you ever tested the file
copying speed? Have you been able to see speeds nearer to 10MB/s rather
than the 6.8MB/s speeds I saw when using a Linux distro?

> Obviously, the performance you get depends on the spec of the
> hardware used.

If you are really serving lots of files and maybe big ones at that,
then the performance of the disks is a significant issue.

Not with 320GB and larger drives. What is an issue are the various
bottlenecks elsewhere within the rest of the system and the quality of
the OS software. For this work, you can safely underclock the CPU by a
considerable ratio (provided you don't land up underclocking the memory
and other buses in the process).

> http://www.smallnetbuilder.com/content/view/30571/77/

Thanks, I shall take a look.

> I don't think the encumbent FS (which, btw, was, and still is, FAT32
> created by a Canon A720 IS camera) is relevant when it comes to using a
> partition editor (which is what got hung up over the 1KB _sector_size_
> being reported by the SD card - _not_ cluster size, please note!).

But in order to boot GNU/Linux off this device, if you are using it as the
root and boot filesystem, it would have to reformat the file system from
FAT 32 to ext3, otherwise you would have to use something like linuxrc to
point to the real root and boot filesystem, in which case, what would
be the point of booting off it at all.

The latest FreeNAS install CD is configured to be able to act as a
'Live CD' able to make use of a dos formatted floppy to store the
configuration parameters or use a flash drive instead. Its install to
flash drive option seems to be broken compared to the earlier versions
which _did_ work.

Luckily, FreeNAS can be downloaded as a flash boot disk image file, as
well as a CD iso image so I was able to go that route to create the
flash drive install.

> Well, I slung an old 3GB laptop drive into a USB enclosure and the
> install proceeded smoothly (if rather slowly) to the point where I could
> apt-get install the webmin software and manage it remotely over the lan
> via a web browser from my desktop machine.

You are making progress at last.

> I have to say, I wasn't over impressed by the webmin interface

I never use such things myself and actually avoid them.

> the same did not appear to be true for the 500GB disk's settings.

What settings do you actually want to change?

Well, the settings appeared to be on slow PIO 'safe' settings and I
wanted to select the higher performance DMA mode. I could make the
various selections and "apply" them, but on returning to this setup
page, they'd reverted back to the defaults.

The speed test result suggested these settings were in no way linked to
reality. This lack of linkage to reality is not limited to webmin in an
Ubuntu setting alone - I see a similar effect with FreeNAS's interface
status resolutely refusing to reflect the changes to the MTU size,
stubbornly reporting an MTU of 1500 regardless of the actual changes
applied elsewhere. I _know_ the applied changes are actually applied
since it effects the over the wire speed - the last change was from an
MTU of 1600 back to 1500 which improved the write speed from just below
20MB/s to 21.5MB/s. The 1600 setting was a temporary test value I'd
forgotten to restore back to 1500 a few months back :-(

> Of course, I'm not following exactly the same hardware path, but if
> there is anything to his finding that the Ubuntu server install gave
> better performance than the FreeNAS one on _the_same_hardware

Well Ubuntu will be using ext3 filesystem, and you said FreeNAS was a
BSD implementation so that would be using a BSD type filesystem. I
do not know how performances would compare, have you tried to find
any comparison reviews?

The FreeNAS OS handles more than just the native BSD file systems, it
is also able to work with NTFS and Linux's Ext2 and Ext3 FSes. I've
elected to use Ext2 since my win2k boxes can read/write to disks thus
formatted (either fitted directly or, the main use, as external
USB/Firewire connected drives). Of course, it matters not what FS is
used on the NAS box drives with regard to the network connected PCs.

My original testing of FreeNAS used the native FS but I quickly
realised that I could equally well use Ext3 or Ext2 which would allow me
to swap more easily between FreeNAS and a linux based NAS solution. I
don't think there was any speed benefit in using the native format, but
there sure was a considerable wastage of disk capacity. When the FS
assigns 8% of a 500GB drive (458GiB actually) for 'spare sectors' the
resulting loss of some 36GB of capacity is not to be sneezed at. At
least with Ext2, I could trim this back to a more reasonable 400MB (but
even so, the FS overhead is still a good 4 or 5GB chunk taken out of
each of the four 1TB drives currently fitted).

I've managed to get FreeNAS onto the test 'box'. That too ran into
trouble installing onto a USB pen drive (I don't think the earlier
versions had any such problem installing to a USB flash drive from the
CD setup disk). However, I was able to copy the flash image version
'directly' using the Physdiskwrite utility and this booted up ok.

An interesting exercise because, once I'd tuned everthing, I was seeing
almost 18MB/s writes but getting just shy of 30MB/s reads out of this
old MoBo! That it must be remembered is with the old 96% full 500GB IDE
drive. The newer build was only getting about an extra 2MB/s on writes
until I changed the MTU back to 1500 to gain another 1.5 to 2MB/s
(around the 21.5 to 22MB/s mark) and a mere 25MB/s on reads, almost
5MB/s slower!

I'm almost certain that a Debian based server box will still have
performance issues, however, while I'm playing around with the test
'box' I might revisit the latest version of the ClarkConnect project[1]
(and possibly one or two other contenders) whilst I'm waiting for
another FreeNAS update to materialise which might offer some improvement
over the current setup.

[1] I've just remembered why I ditched the ClarkConnect server OS. I was
seeing wildly varying read/write speeds which spoilt the whole concept
of performance. If it had been able to sustain its top speed, it would
have been a clear winner.

It's quite possible that the issue has now been resolved or was only
there with the particular hardware mix I was using at the time. Since
this also had a usable webGUI, it's worth reconsidering except it didn't
offer a flash memory install option which is a crying shame. It's been a
couple of years since then, so they might have introduced a flash drive
boot option by now, so it would be worth taking another look at what's
on offer.

--
Regards, John.

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