Tuning LTO Drives to improve write speed

[bamber]

I have just installed a Quantum ATL M1500 LTO unit, this has 2 tape units and is connected to a Sun E250.

It is connected via LVD scsi and has a network interface of 100mb's

When backing up it seems to be writing at 1.5 to 1.7 K/B's per second whereas I was expecting a considerably faster write speed from all the gumph that you read of around 10 - 20 Mb's per second.

We are running Solaris 2.6 with Networker 6.0.1

Does anybody have any suggestions ?????

 

[ulsj]

Hi!

Check the network card set speed to 10 or 100 not autodetect
and set the duplex setting to full or half not autodetect

/Ulf

 

[bamber]

Hi Ulf

Thanks for the suggestion.

I have now hard set the switch and also updated the etc/system file to force full 100.

However I still get the same results, It's annoying because one of the servers that I plan to use the lto for already takes 30hrs plus to backup on a full backup.

I am now waiting for MTI to get back to me.

 

[oodeano]

The usual test to try is a file copy to the backup server from the backup client. This will determine if it's a tape drive problem or a client or network problem.

 

[bamber]

Hi Guys

Thanks for your advice.

The problem was tracked down to two thing, we installed the Solaris 8 st.conf patch (Yes I know we are running 2.6) and also changed the st.conf.

A local backup of the host server worked at 17mb's and a networked backup at 7.5 Mbs per second.

I think the only way to further improve this is to upgrade to a gig nic and firbre channel.

By the way the patch added is in the latest reccommended patch bundle from Sun.

Bamber

 

[BW78]

100 Mb\s = 12,5 MB/s 60%= 7,5 MB/s

That´s ok for a 100 Mbit Network and your bottleleck.

 

[jimbopalmer]

I wrote a S95ndd in my rc3.d of my solaris servers to give versions upto 2.7 more ethernet buffering. (Solaris 8 finally changes the default from 8k to 24k (5 packets to 16 packets))

#!/bin/sh
# Set the TCP hiwater marks to 64K to improve SunSwift SBus
# Adapter performace. JJP 22-Aug-2000
case "$1" in
'start')
echo "Setting local kernel parameters...\c"
ndd -set /dev/tcp tcp_xmit_hiwat 65535
ndd -set /dev/tcp tcp_recv_hiwat 65535
ndd -set /dev/tcp tcp_cwnd_max 65534
echo ""
;;
'stop')
echo "No kernel parameters changed."
;;

*)
echo "Usage:$0 {start|stop}"
;;
esac
exit 0 I tried to remain child-like, all I acheived was childish.