Re: Backup to USB works but to NAS fails

OH HECK, what was that 5,4,3 rule of ethernet?

server-hub-linksys-linksys2-nas

You sound like you may be hitting an inherent limit of ethernet (should they
not have abolished that, sorry, don't know).

"Another Brian" <notbrian@xxxxxxxxxxxxxxx> wrote in message
news:e98J$ZQBIHA.5328@xxxxxxxxxxxxxxxxxxxxxxx
Thank you, David, for replying. I've put my answers in-line. You've given
me a lot of food for thought.

Brian Bygland

"David Barnes" <david at bitsolve dot com .nospam.ignore.net> wrote in
message news:%23UFAZcFBIHA.5980@xxxxxxxxxxxxxxxxxxxxxxx
What type of cable do you have between the NAS box and the server.
How far is it?

(I'm not at church so I doing this from memory) All cables are CAT5. There
is a 30' stretch from the server to a hub (which doesn't have any open
slots). From there is a 20' length to a LinkSys router that is configured
to run just as a switch/hub (DHCP is disabled). Next is the long haul of
150', maybe a bit longer, to another LinkSys router used as a switch/hub.
Then 3' to the NAS drive. If we put another network card in the server we
could run a single cable directly from the server to the NAS.

Can you reduce things down to one decent switch.
Poor network throughput, is most commonly, use of cheap 25$ switches.
Netgear FS 5xx series are noticibly faster than the FS 1xx series.
HP 2424M, 2524M etc is even faster
Top-end Cisco and HP units are a bit faster again.

What else is on the LAN

On the LAN we have the server connecting to the first hub. That hub has
four workstations, two network printers, and a line to the LinkSys router.
That LinkSys router has two workstations plus wireless (usually only one
wireless PC supported) and two lines to other wireless LinkSys routers.
One of those LinkSys is used only to support the same wireless PC when
it's moved around the church. The other line goes to the far end of the
church to a fourth LinkSys wireless router. This fourth router has the NAS
drive and supports wireless for that roaming laptop.

On a busy network HUB (not switch) the CSMA method(protocol) that
ethernet uses to avoid collisions and to allow multiple systems to share
the network, causes an overhead. This reduces throughput to as low as 10%
of the rated speed.
On a good switch with only 2 nodes, you are doing well if you can push
the network to 80%.

One factor that may be an issue is signing. By default SBS (and win2k3
and XP) attempt to encrypt and sign the data sent over the lan.
Turning off signing and encryption can improve performance. My thoughts
are that you don't need to guard your lan against a rouge machine
'sniffing' data etc. (sort of big bank type security)

Can you suggest how to turn this off?

If you have cat-5 cable (rj45 plugs) in place then, unless it's very poor
quality or badly terminated, it will carry 100MB lan with no problem and
SHOULD do gig without issue.

to upgrade to gig, you would need to replace the NIC in the server,
change the switches to 10/100/1000 and make sure the NAS box has a GIG
nic as well.

The NAS supports GIG. I'd add a second NIC to the server with a dedicated
line to the NAS.

The server 'lights out' is probably exhaustion of the NP Pool.
What AV do you have?
Is it set to scan on reads and writes, or just writes?
Have you added the full set of sbs exclusions?

We're using McAfee AV. I'll have to check its settings for the read/write
scanning and the exclusion list

See MS KB 822158 and 823166
The following (unless stated) need to be EXCLUDED from On-Access
scanning


C:\Program Files\Exchsrvr
D:\Program Files\Exchsrvr
C:\Windows\system32\Inetsrv
C:\Windows\IIS Temporary Compressed Files
C:\Windows\ntds
C:\Windows\ntfrs
C:\Windows\sysvol - - - - - Exclude
C:\Windows\sysvol\domain - - - Scan
C:\Windows\sysvol\domain\DO_NOT_Remove. - Exclude
C:\Windows\sysvol\domain\Policies - - Scan
C:\Windows\sysvol\domain\Scripts - - Scan
C:\Windows\sysvol\staging - - - Exclude
C:\Windows\sysvol\staging areas - - Exclude
C:\Windows\sysvol\sysvol - - - Exclude
C:\Windows\system32\Wins
C:\Windows\system32\DNS
C:\Windows\system32\config
C:\Windows\system32\DHCP
C:\Windows\system32\logfiles
C:\Windows\system32\spool
C:\inetpub\mailroot
C:\Program Files\Microsoft Windows Small Business
Server\Networking\POP3\Failed Mail\
C:\Program Files\Microsoft Windows Small Business
Server\Networking\POP3\Incoming Mail\
C:\System Volume Information\
C:\WINDOWS\Cluster\
C:\WINDOWS\system32\MsDtc\
C:\WINDOWS\system32\NtmsData\
C:\Program Files\Microsoft SQL Server\
D:\Program Files\Microsoft SQL Server\
D:\System Volume Information\
C:\fax\
D:\fax\

Any other alternate location containing Exchange or SQL
Do you have any defragmentation software? I have seen servers do this
with diskeeper. Not been able to point the finger, but removing it has
made the problem go away.

We don't have any extra defragmentation sw. I'll check on the volumes
fragmentation and utilisation later today.

How fragmented are the volumes? Fragmentation has an impact on NP Pool
usage under high IO load (EG Backup)

What's the utilisation on the volumes? (how full are the drives) The
fuller they are, the slower they run.

You may find memory/resource exhaustion is happening as a result of
loading on the Network card.
Sometimes tweaking the params can help.
Easiest fix though is to add more ram.. How much RAM do you have?
Are you using the PAE or /3GIG switch?

From memory I think we only have 768MB on the server. I should really try
bumping that up as high as we can afford.
What is the PAE or /3GIG switch?

The other side of the coin is that the ROOT CAUSE resource exhaustion may
not be occuring on the server, but the NAS box. Data then backs up over
the LAN and backup keeps pushing untill it exhausts local resources.
Killing the backup would probably take some 35 mins plus for the server
to recover and be normally usable.

Ouch!

On a side note, the HDD max sustained throughput is probably in the order
of 20 to 60 MB/s WAY lower than the USB thearetical throughput and about
right for a 100MB LAN. In theory the HDD in your server or your NAS box
are the limiting factors.
The very latest Seagate Barracuda 7200.11 drives are only just reaching
105MB/s internal sustained rate.

Also..
NTBACKUP.exe appears to be crippled when using a network drive (share) as
the output and even worse when you are trying to backup data held on a
share.


Sorry for throwing this in so many directions at once.
But this can be one of many causes, or a combination of 2, 3 or more..

David Barnes





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