Thanks for the responses but I am still confused about how the paths are determined. For example, lets say I have a FAS6030C (Node1 and Node2) running Data Ontap 7.2.1 with each head having 2 target ports each in a switched fibre fabric. In this fabric, I have a Windows host (running Snapdrive 4.2.1 and DSM 3.0) with a dual port fibre card. I create lun0 on Node1 from the Windows host via Snapdrive. How is the path chosen by the FAS6030C? Is there a round robin algorithm which gives out the target port on Node1 to the Windows host?
-----Original Message----- From: Paul Rosham [mailto:paulrosham@yahoo.com.au] Sent: Monday, April 16, 2007 11:26 PM To: 'Jack Lyons'; 'Nils Vogels' Cc: Mike Ball; toasters@mathworks.com Subject: RE: Information on how Netapp single_image mode works
In addition, anything with a reasonable NVRAM/Cluster interconnect setup (i.e. 3000, 6000 series) the additional latency of the request passing to the correct head via the cluster interconect is almost negligible.
-----Original Message----- From: owner-toasters@mathworks.com [mailto:owner-toasters@mathworks.com] On Behalf Of Jack Lyons Sent: Tuesday, 17 April 2007 11:10 AM To: Nils Vogels Cc: Mike Ball; toasters@mathworks.com Subject: Re: Information on how Netapp single_image mode works
one caveat, based on my experience
the host based software will see all paths to the filer as equal, so if you hit the WWPN on the "other" head of the cluster, you will get an error message and an ASUP. It is annoying, and as far as I know, not a problem.
Jack
Nils Vogels wrote:
Hey Mike,
On 4/16/07, Mike Ball MBall@datalink.com wrote:
I am trying to find additional information on how Netapp single_image
mode works in a clustered environment as it pertains to pathing. Single_image mode pulls all the WWPN's from the Netapp cluster and presents it to the SAN as one WWNN. What I would like to know is how paths are determined from hosts to cluster nodes if no target portals
are defined?
There will be multiple paths available (at least 2, one for ClusterA, one for ClusterB) and you generally will need host-based path selection software to select the active one.
Some software selects on 'Most Recently Used', other selects on fixed path, this may vary per multipathing-software.
http://now.netapp.com/NOW/knowledge/docs/ontap/rel72/html/ontap/bsag/8cl us-f4.htm
-----Original Message----- From: Mike Ball [mailto:MBall@datalink.com] Sent: Tuesday, April 17, 2007 7:56 AM To: toasters@mathworks.com Subject: RE: Information on how Netapp single_image mode works
Thanks for the responses but I am still confused about how the paths are determined. For example, lets say I have a FAS6030C (Node1 and Node2) running Data Ontap 7.2.1 with each head having 2 target ports each in a switched fibre fabric. In this fabric, I have a Windows host (running Snapdrive 4.2.1 and DSM 3.0) with a dual port fibre card. I create lun0 on Node1 from the Windows host via Snapdrive. How is the path chosen by the FAS6030C? Is there a round robin algorithm which gives out the target port on Node1 to the Windows host?
-----Original Message----- From: Paul Rosham [mailto:paulrosham@yahoo.com.au] Sent: Monday, April 16, 2007 11:26 PM To: 'Jack Lyons'; 'Nils Vogels' Cc: Mike Ball; toasters@mathworks.com Subject: RE: Information on how Netapp single_image mode works
In addition, anything with a reasonable NVRAM/Cluster interconnect setup (i.e. 3000, 6000 series) the additional latency of the request passing to the correct head via the cluster interconect is almost negligible.
-----Original Message----- From: owner-toasters@mathworks.com [mailto:owner-toasters@mathworks.com] On Behalf Of Jack Lyons Sent: Tuesday, 17 April 2007 11:10 AM To: Nils Vogels Cc: Mike Ball; toasters@mathworks.com Subject: Re: Information on how Netapp single_image mode works
one caveat, based on my experience
the host based software will see all paths to the filer as equal, so if you hit the WWPN on the "other" head of the cluster, you will get an error message and an ASUP. It is annoying, and as far as I know, not a problem.
Jack
Nils Vogels wrote:
Hey Mike,
On 4/16/07, Mike Ball MBall@datalink.com wrote:
I am trying to find additional information on how Netapp single_image
mode works in a clustered environment as it pertains to pathing. Single_image mode pulls all the WWPN's from the Netapp cluster and presents it to the SAN as one WWNN. What I would like to know is how paths are determined from hosts to cluster nodes if no target portals
are defined?
There will be multiple paths available (at least 2, one for ClusterA, one for ClusterB) and you generally will need host-based path selection software to select the active one.
Some software selects on 'Most Recently Used', other selects on fixed path, this may vary per multipathing-software.
Hi Mike The path is never determined by the storage device. The server/host (or it's multipath implementation) determines that. Remember "initiator" and "target" - the initiator decides by specifying a particular target WWPN.
I haven't played with DSM3.0 so I can't answer that part, but the NetApp ESX Host Utilities analyzes the target WWPNs and figures out preferred paths to avoid using proxy paths.
If you look at the link Vic gave, you can see in the picture that there are 8 paths (2 server HBAs each going to a switch with 4 paths to controllers). "lun_1" should be accessed through ports on "Filer X". The way you tell which ports are the ones is the "fcp config" or "fcp show adapters" on the controller on which you created the LUN. Look at the first digit of the 5th octet of the portname, which is usually either 8 for one controller or 9 for the other.
Here's the decoder on this: 50:0a:09:83:82:00:96:d5 5 = IEEE Registered Name format 00a098 = OUI for NetApp - just like for Ethernet 3 = Port number on this controller 8 = Which head (usually 8 or 9) 0096d5 = Unique vendor-assigned part. Usually determined by one of the hardware WWNs on one of the ports, then the same one is soft-assigned to all the other targets. Also written to disk in case you swap heads (upgrade, etc.) so it keeps it.
The asup error (FCP Partner Path Misconfigured) that Jack mentioned indicates that the server is using a non-preferred path. There could be a performance impact, but other than the annoyance of lots of asups and corresponding case notifications, that's it. You can figure out which server it is by figuring out which LUN, which you do with "lun stats -o [lun_path]"
homer*> lun stats -o /vol/peterwintest/w2k3ent (23 hours, 20 minutes, 50 seconds) Read (kbytes) Write (kbytes) Read Ops Write Ops Other Ops QFulls Partner Ops Partner KBytes 5 0 3 0 148 0 0 0 /vol/vmfstest2/vmfstest2 (23 hours, 20 minutes, 50 seconds) Read (kbytes) Write (kbytes) Read Ops Write Ops Other Ops QFulls Partner Ops Partner KBytes 686582 96097 21313 23149 396 0 0 0
If you see "Partner Ops" and "Partner Kbytes" then a server using that LUN is using a non-preferred path, and you need to check the multipath settings on that server. You can reset the counters with "lun stats -z [lun_path]".
Share and enjoy!
Peter
-----Original Message----- From: Mike Ball [mailto:MBall@datalink.com] Sent: Tuesday, April 17, 2007 4:56 AM To: toasters@mathworks.com Subject: RE: Information on how Netapp single_image mode works
Thanks for the responses but I am still confused about how the paths are determined. For example, lets say I have a FAS6030C (Node1 and Node2) running Data Ontap 7.2.1 with each head having 2 target ports each in a switched fibre fabric. In this fabric, I have a Windows host (running Snapdrive 4.2.1 and DSM 3.0) with a dual port fibre card. I create lun0 on Node1 from the Windows host via Snapdrive. How is the path chosen by the FAS6030C? Is there a round robin algorithm which gives out the target port on Node1 to the Windows host?
-----Original Message----- From: Paul Rosham [mailto:paulrosham@yahoo.com.au] Sent: Monday, April 16, 2007 11:26 PM To: 'Jack Lyons'; 'Nils Vogels' Cc: Mike Ball; toasters@mathworks.com Subject: RE: Information on how Netapp single_image mode works
In addition, anything with a reasonable NVRAM/Cluster interconnect setup (i.e. 3000, 6000 series) the additional latency of the request passing to the correct head via the cluster interconect is almost negligible.
-----Original Message----- From: owner-toasters@mathworks.com [mailto:owner-toasters@mathworks.com] On Behalf Of Jack Lyons Sent: Tuesday, 17 April 2007 11:10 AM To: Nils Vogels Cc: Mike Ball; toasters@mathworks.com Subject: Re: Information on how Netapp single_image mode works
one caveat, based on my experience
the host based software will see all paths to the filer as equal, so if you hit the WWPN on the "other" head of the cluster, you will get an error message and an ASUP. It is annoying, and as far as I know, not a problem.
Jack
Nils Vogels wrote:
Hey Mike,
On 4/16/07, Mike Ball MBall@datalink.com wrote:
I am trying to find additional information on how Netapp single_image
mode works in a clustered environment as it pertains to pathing. Single_image mode pulls all the WWPN's from the Netapp cluster and presents it to the SAN as one WWNN. What I would like to know is how paths are determined from hosts to cluster nodes if no target portals
are defined?
There will be multiple paths available (at least 2, one for ClusterA, one for ClusterB) and you generally will need host-based path selection software to select the active one.
Some software selects on 'Most Recently Used', other selects on fixed path, this may vary per multipathing-software.
I'd like to ask, "Are you wanting to understand how SnapDrive chooses the correct path?' and, "Do you have path error messages on the FIler when you connect to LUNs via SnapDrive?"
Vaughn
On 4/17/07, Learmonth, Peter Peter.Learmonth@netapp.com wrote:
Hi Mike The path is never determined by the storage device. The server/host (or it's multipath implementation) determines that. Remember "initiator" and "target" - the initiator decides by specifying a particular target WWPN.
I haven't played with DSM3.0 so I can't answer that part, but the NetApp ESX Host Utilities analyzes the target WWPNs and figures out preferred paths to avoid using proxy paths.
If you look at the link Vic gave, you can see in the picture that there are 8 paths (2 server HBAs each going to a switch with 4 paths to controllers). "lun_1" should be accessed through ports on "Filer X". The way you tell which ports are the ones is the "fcp config" or "fcp show adapters" on the controller on which you created the LUN. Look at the first digit of the 5th octet of the portname, which is usually either 8 for one controller or 9 for the other.
Here's the decoder on this: 50:0a:09:83:82:00:96:d5 5 = IEEE Registered Name format 00a098 = OUI for NetApp - just like for Ethernet 3 = Port number on this controller 8 = Which head (usually 8 or 9) 0096d5 = Unique vendor-assigned part. Usually determined by one of the hardware WWNs on one of the ports, then the same one is soft-assigned to all the other targets. Also written to disk in case you swap heads (upgrade, etc.) so it keeps it.
The asup error (FCP Partner Path Misconfigured) that Jack mentioned indicates that the server is using a non-preferred path. There could be a performance impact, but other than the annoyance of lots of asups and corresponding case notifications, that's it. You can figure out which server it is by figuring out which LUN, which you do with "lun stats -o [lun_path]"
homer*> lun stats -o /vol/peterwintest/w2k3ent (23 hours, 20 minutes, 50 seconds) Read (kbytes) Write (kbytes) Read Ops Write Ops Other Ops QFulls Partner Ops Partner KBytes 5 0 3 0 148 0 0 0 /vol/vmfstest2/vmfstest2 (23 hours, 20 minutes, 50 seconds) Read (kbytes) Write (kbytes) Read Ops Write Ops Other Ops QFulls Partner Ops Partner KBytes 686582 96097 21313 23149 396 0 0 0
If you see "Partner Ops" and "Partner Kbytes" then a server using that LUN is using a non-preferred path, and you need to check the multipath settings on that server. You can reset the counters with "lun stats -z [lun_path]".
Share and enjoy!
Peter
-----Original Message----- From: Mike Ball [mailto:MBall@datalink.com] Sent: Tuesday, April 17, 2007 4:56 AM To: toasters@mathworks.com Subject: RE: Information on how Netapp single_image mode works
Thanks for the responses but I am still confused about how the paths are determined. For example, lets say I have a FAS6030C (Node1 and Node2) running Data Ontap 7.2.1 with each head having 2 target ports each in a switched fibre fabric. In this fabric, I have a Windows host (running Snapdrive 4.2.1 and DSM 3.0) with a dual port fibre card. I create lun0 on Node1 from the Windows host via Snapdrive. How is the path chosen by the FAS6030C? Is there a round robin algorithm which gives out the target port on Node1 to the Windows host?
-----Original Message----- From: Paul Rosham [mailto:paulrosham@yahoo.com.au] Sent: Monday, April 16, 2007 11:26 PM To: 'Jack Lyons'; 'Nils Vogels' Cc: Mike Ball; toasters@mathworks.com Subject: RE: Information on how Netapp single_image mode works
In addition, anything with a reasonable NVRAM/Cluster interconnect setup (i.e. 3000, 6000 series) the additional latency of the request passing to the correct head via the cluster interconect is almost negligible.
-----Original Message----- From: owner-toasters@mathworks.com [mailto:owner-toasters@mathworks.com] On Behalf Of Jack Lyons Sent: Tuesday, 17 April 2007 11:10 AM To: Nils Vogels Cc: Mike Ball; toasters@mathworks.com Subject: Re: Information on how Netapp single_image mode works
one caveat, based on my experience
the host based software will see all paths to the filer as equal, so if you hit the WWPN on the "other" head of the cluster, you will get an error message and an ASUP. It is annoying, and as far as I know, not a problem.
Jack
Nils Vogels wrote:
Hey Mike,
On 4/16/07, Mike Ball MBall@datalink.com wrote:
I am trying to find additional information on how Netapp single_image
mode works in a clustered environment as it pertains to pathing. Single_image mode pulls all the WWPN's from the Netapp cluster and presents it to the SAN as one WWNN. What I would like to know is how paths are determined from hosts to cluster nodes if no target portals
are defined?
There will be multiple paths available (at least 2, one for ClusterA, one for ClusterB) and you generally will need host-based path selection software to select the active one.
Some software selects on 'Most Recently Used', other selects on fixed path, this may vary per multipathing-software.
I haven't played with DSM3.0 so I can't answer that part, but the NetApp ESX Host Utilities analyzes the target WWPNs and figures out preferred paths to avoid using proxy paths.
I haven't used the Netapp ESX Host utilities, but we are using a script that looks at the paths available for each lun and alternates it between the paths on the primary head. (nothing like testing the script to discover a logic error will generate a lot of ASUP's)
What is included in the NetApp ESX host utilities that you find useful?
config_mpath: A tool that automatically figures out the paths and spreads the LUNs across preferred paths.
It doesn't prevent ESX from failing over to a non-pref path. It seems ESX grabs the first available path in canonical(?) order, which about half the time will be non-preferred. It looks something like this:
[root@jw-esx1 root]# esxcfg-mpath -l Disk vmhba1:0:0 /dev/sdc (81926MB) has 4 paths and policy of Fixed FC 28:0.0 210000e08b865d42<->500a09818697b5b1 vmhba1:0:0 On active preferred FC 28:0.0 210000e08b865d42<->500a09829697b5b1 vmhba1:1:0 On FC 28:0.1 210100e08ba65d42<->500a09828697b5b1 vmhba2:0:0 On FC 28:0.1 210100e08ba65d42<->500a09819697b5b1 vmhba2:1:0 On
Disk vmhba1:0:1 /dev/sdd (81926MB) has 4 paths and policy of Fixed FC 28:0.0 210000e08b865d42<->500a09818697b5b1 vmhba1:0:1 On FC 28:0.0 210000e08b865d42<->500a09829697b5b1 vmhba1:1:1 On FC 28:0.1 210100e08ba65d42<->500a09828697b5b1 vmhba2:0:1 On active preferred FC 28:0.1 210100e08ba65d42<->500a09819697b5b1 vmhba2:1:1 On ^ ^ If you look real close at the digit above the first ^ (assuming email doesn't mess up my alignment), you see it's either 8 or 9, which indicates which controller the port/WWPN is on. The second ^ points at the target portion of the vmhba designation, which matches. The NetApp ESX HU tool looks at the WWPN (that digit in particular), queries the controllers for their LUNs and WWPNs and figures out for each LUN which paths are direct and which are proxy, and simply alternates LUNs for each controller across the two paths. So some LUNs on homer(*) go via vmhba1:0:x and some via vmhba2:0:x. For bart's LUNs, they go through vmhba1:1:x or vmhba2:1:x.
The way ESX multipathing fails over, it grabs the first available path in the order listed. So if we start with vmhba1:0:0 and that fails, it will go to vmhba1:1:0, which is a proxy path, and not what you want. For those LUNs "balanced" on vmhba2:0:x (sdd in the example above), if that link fails, and the rest of the links are up, those LUNs get moved to vmhba1:0:x (first in the list), which is a non-proxy path which is what you want.
It all goes back the way it's supposed to when you plug the cable back in.
I hope this makes sense...
Enjoy!
Peter
*By the way, here's the target port info for bart and homer: homer> fcp show adapters Slot: 0c FC Portname: 50:0a:09:81:86:97:b5:b1 (500a09818697b5b1) Slot: 0d FC Portname: 50:0a:09:82:86:97:b5:b1 (500a09828697b5b1)
bart> fcp show adapters Slot: 0c FC Portname: 50:0a:09:81:96:97:b5:b1 (500a09819697b5b1) Slot: 0d FC Portname: 50:0a:09:82:96:97:b5:b1 (500a09829697b5b1) ^ ^ port | | node/controller
(Slightly snipped)
Peter
-----Original Message----- From: Jack Lyons [mailto:jack1729@gmail.com] Sent: Tuesday, April 17, 2007 5:43 PM To: Learmonth, Peter Cc: Mike Ball; toasters@mathworks.com Subject: Re: Information on how Netapp single_image mode works
I haven't played with DSM3.0 so I can't answer that part, but the NetApp ESX Host Utilities analyzes the target WWPNs and figures out preferred paths to avoid using proxy paths.
I haven't used the Netapp ESX Host utilities, but we are using a script that looks at the paths available for each lun and alternates it between the paths on the primary head. (nothing like testing the script to discover a logic error will generate a lot of ASUP's)
What is included in the NetApp ESX host utilities that you find useful?
Hopefully you are using zoning to control what ports the host will see. IF you do not have MPIO software you will have to present the host one path.
-----Original Message----- From: owner-toasters@mathworks.com [mailto:owner-toasters@mathworks.com] On Behalf Of Mike Ball Sent: Tuesday, April 17, 2007 5:56 AM To: toasters@mathworks.com Subject: RE: Information on how Netapp single_image mode works
Thanks for the responses but I am still confused about how the paths are determined. For example, lets say I have a FAS6030C (Node1 and Node2) running Data Ontap 7.2.1 with each head having 2 target ports each in a switched fibre fabric. In this fabric, I have a Windows host (running Snapdrive 4.2.1 and DSM 3.0) with a dual port fibre card. I create lun0 on Node1 from the Windows host via Snapdrive. How is the path chosen by the FAS6030C? Is there a round robin algorithm which gives out the target port on Node1 to the Windows host?
-----Original Message----- From: Paul Rosham [mailto:paulrosham@yahoo.com.au] Sent: Monday, April 16, 2007 11:26 PM To: 'Jack Lyons'; 'Nils Vogels' Cc: Mike Ball; toasters@mathworks.com Subject: RE: Information on how Netapp single_image mode works
In addition, anything with a reasonable NVRAM/Cluster interconnect setup (i.e. 3000, 6000 series) the additional latency of the request passing to the correct head via the cluster interconect is almost negligible.
-----Original Message----- From: owner-toasters@mathworks.com [mailto:owner-toasters@mathworks.com] On Behalf Of Jack Lyons Sent: Tuesday, 17 April 2007 11:10 AM To: Nils Vogels Cc: Mike Ball; toasters@mathworks.com Subject: Re: Information on how Netapp single_image mode works
one caveat, based on my experience
the host based software will see all paths to the filer as equal, so if you hit the WWPN on the "other" head of the cluster, you will get an error message and an ASUP. It is annoying, and as far as I know, not a problem.
Jack
Nils Vogels wrote:
Hey Mike,
On 4/16/07, Mike Ball MBall@datalink.com wrote:
I am trying to find additional information on how Netapp single_image
mode works in a clustered environment as it pertains to pathing. Single_image mode pulls all the WWPN's from the Netapp cluster and presents it to the SAN as one WWNN. What I would like to know is how paths are determined from hosts to cluster nodes if no target portals
are defined?
There will be multiple paths available (at least 2, one for ClusterA, one for ClusterB) and you generally will need host-based path selection software to select the active one.
Some software selects on 'Most Recently Used', other selects on fixed path, this may vary per multipathing-software.
You definitely want to use multipathing software, but with respect to zoning, you need to be able to "see" all the ports that the host might connect to in an outage.
Jack
Wilkinson, Brent wrote:
Hopefully you are using zoning to control what ports the host will see. IF you do not have MPIO software you will have to present the host one path.
-----Original Message----- From: owner-toasters@mathworks.com [mailto:owner-toasters@mathworks.com] On Behalf Of Mike Ball Sent: Tuesday, April 17, 2007 5:56 AM To: toasters@mathworks.com Subject: RE: Information on how Netapp single_image mode works
Thanks for the responses but I am still confused about how the paths are determined. For example, lets say I have a FAS6030C (Node1 and Node2) running Data Ontap 7.2.1 with each head having 2 target ports each in a switched fibre fabric. In this fabric, I have a Windows host (running Snapdrive 4.2.1 and DSM 3.0) with a dual port fibre card. I create lun0 on Node1 from the Windows host via Snapdrive. How is the path chosen by the FAS6030C? Is there a round robin algorithm which gives out the target port on Node1 to the Windows host?
-----Original Message----- From: Paul Rosham [mailto:paulrosham@yahoo.com.au] Sent: Monday, April 16, 2007 11:26 PM To: 'Jack Lyons'; 'Nils Vogels' Cc: Mike Ball; toasters@mathworks.com Subject: RE: Information on how Netapp single_image mode works
In addition, anything with a reasonable NVRAM/Cluster interconnect setup (i.e. 3000, 6000 series) the additional latency of the request passing to the correct head via the cluster interconect is almost negligible.
-----Original Message----- From: owner-toasters@mathworks.com [mailto:owner-toasters@mathworks.com] On Behalf Of Jack Lyons Sent: Tuesday, 17 April 2007 11:10 AM To: Nils Vogels Cc: Mike Ball; toasters@mathworks.com Subject: Re: Information on how Netapp single_image mode works
one caveat, based on my experience
the host based software will see all paths to the filer as equal, so if you hit the WWPN on the "other" head of the cluster, you will get an error message and an ASUP. It is annoying, and as far as I know, not a problem.
Jack
Nils Vogels wrote:
Hey Mike,
On 4/16/07, Mike Ball MBall@datalink.com wrote:
I am trying to find additional information on how Netapp single_image
mode works in a clustered environment as it pertains to pathing. Single_image mode pulls all the WWPN's from the Netapp cluster and presents it to the SAN as one WWNN. What I would like to know is how paths are determined from hosts to cluster nodes if no target portals
are defined?
There will be multiple paths available (at least 2, one for ClusterA, one for ClusterB) and you generally will need host-based path selection software to select the active one.
Some software selects on 'Most Recently Used', other selects on fixed path, this may vary per multipathing-software.
Yes, if you have MPIO software you zone a port on each head. Otherwise your OS will see two disks and cause issues. ESX by default is MPIO capable, some flavors of unix are tolerable. Windows you can have issues if you zone two paths without MPIO software. Single Image allows any port to access any disk regardless of head ( as I understand it )which would mean you need MPIO software to zone more than one storage port to the host.
-----Original Message----- From: Jack Lyons [mailto:jack1729@gmail.com] Sent: Tuesday, April 17, 2007 6:37 PM To: Wilkinson, Brent Cc: Mike Ball; toasters@mathworks.com Subject: Re: Information on how Netapp single_image mode works
You definitely want to use multipathing software, but with respect to zoning, you need to be able to "see" all the ports that the host might connect to in an outage.
Jack
Wilkinson, Brent wrote:
Hopefully you are using zoning to control what ports the host will
see.
IF you do not have MPIO software you will have to present the host one path.
-----Original Message----- From: owner-toasters@mathworks.com
[mailto:owner-toasters@mathworks.com]
On Behalf Of Mike Ball Sent: Tuesday, April 17, 2007 5:56 AM To: toasters@mathworks.com Subject: RE: Information on how Netapp single_image mode works
Thanks for the responses but I am still confused about how the paths
are
determined. For example, lets say I have a FAS6030C (Node1 and Node2) running Data Ontap 7.2.1 with each head having 2 target ports each in
a
switched fibre fabric. In this fabric, I have a Windows host (running Snapdrive 4.2.1 and DSM 3.0) with a dual port fibre card. I create
lun0
on Node1 from the Windows host via Snapdrive. How is the path chosen
by
the FAS6030C? Is there a round robin algorithm which gives out the target port on Node1 to the Windows host?
-----Original Message----- From: Paul Rosham [mailto:paulrosham@yahoo.com.au] Sent: Monday, April 16, 2007 11:26 PM To: 'Jack Lyons'; 'Nils Vogels' Cc: Mike Ball; toasters@mathworks.com Subject: RE: Information on how Netapp single_image mode works
In addition, anything with a reasonable NVRAM/Cluster interconnect
setup
(i.e. 3000, 6000 series) the additional latency of the request passing to the correct head via the cluster interconect is almost negligible.
-----Original Message----- From: owner-toasters@mathworks.com
[mailto:owner-toasters@mathworks.com]
On Behalf Of Jack Lyons Sent: Tuesday, 17 April 2007 11:10 AM To: Nils Vogels Cc: Mike Ball; toasters@mathworks.com Subject: Re: Information on how Netapp single_image mode works
one caveat, based on my experience
the host based software will see all paths to the filer as equal, so
if
you hit the WWPN on the "other" head of the cluster, you will get an error message and an ASUP. It is annoying, and as far as I know, not
a
problem.
Jack
Nils Vogels wrote:
Hey Mike,
On 4/16/07, Mike Ball MBall@datalink.com wrote:
I am trying to find additional information on how Netapp
single_image
mode works in a clustered environment as it pertains to pathing. Single_image mode pulls all the WWPN's from the Netapp cluster and presents it to the SAN as one WWNN. What I would like to know is how
paths are determined from hosts to cluster nodes if no target
portals
are defined?
There will be multiple paths available (at least 2, one for ClusterA,
one for ClusterB) and you generally will need host-based path selection software to select the active one.
Some software selects on 'Most Recently Used', other selects on fixed
path, this may vary per multipathing-software.
-
Jack Lyons -
Learmonth, Peter -
Mike Ball -
Rozumny, Vic -
Vaughn Stewart -
Wilkinson, Brent