Linux dm-multipath and SAN/iQ 8.5

[eschneid]

Is anyone using dm-multipath with Linux and SAN/iQ 8.5? We tested a few years ago, but we had a multi-site SAN, so it wouldn't work across the router. We have since "flattened" the network and removed the router. VMware multipathing is working great now. We are assuming Linux should work now also.


Current SAN config:
10 Dell 2950s (6 SAS and 4 SATA)
Dedicated 10.x.x.x network
2 clusters for SAS and SATA - 2 VIPs

All servers are m600 Dell Blades.

4 x ESX 4 update 2 hosts using VMware round-robin configured according to LH/HP documentation. This has worked great for the last 2 weeks and both paths get equal traffic.


1 x RHEL 5.5 system with 2 storage NICs. Can I use round robin? Any hints on the config.

Thanks.

/etc/multipathd.conf
blacklist {
devnode "^sda$"
devnode "(ram|raw|loop|fd|md|dm-|sr|scd|st)[0-9]*"
devnode "^hd[a-z]"
}
defaults {
user_friendly_names yes
no_path_retry 1
}
multipaths {
multipath {
wwid 36000eb37918503e20000000000000959p1
alias mpath0p1
}
}
devices {
device {
vendor "LEFTHAND"
product "iSCSIDisk"
path_grouping_policy multibus
getuid_callout "/sbin/scsi_id -g -u -s /block/%n"
features "1 queue_if_no_path"
path_checker readsector0
failback immediate
}
}

[eschneid]

This config will send traffic down both NICs. Maybe it would be better to bond the NICs with Linux?

[Chris Wigglesworth]

We are using dm-multipath with RHEL5 and SAN/iQ 8.5 (although not yet in production) and it seems to work well from our testing so far. We have been using round robin. This page was usual to us in setting it up, even though it is focused around Equalogic.

http://linfrastructure.blogspot.com/2008/02/multipath-and-equallogic-iscsi.html