Re: Backup to USB works but to NAS fails
- From: "David Barnes" <david at bitsolve dot com .nospam.ignore.net>
- Date: Mon, 1 Oct 2007 19:15:47 +0100
What type of cable do you have between the NAS box and the server.
How far is it?
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 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)
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 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?
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 and 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.
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?
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.
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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