Sun StorEdge[TM] Network FC Switch: SL loop instability when too many initiators exist

Asset ID:	1-72-1007788.1
Update Date:	2018-01-03
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Solution Type Problem Resolution Sure

Solution 1007788.1 : Sun StorEdge[TM] Network FC Switch: SL loop instability when too many initiators exist

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Sun Network Switch

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PLA-Support>Sun Systems>SAND>Network>SN-SND: Sun Network Ethernet Switches

PreviouslyPublishedAs
210774

Symptoms

The Sun StorEdge FC Switch (Sanbox 1G) in Segmented Loop (SL) mode has limitations on the number of initiators allowed in a SL zone.

Private loop SANs that were within SL qualification limits when first configured can grow over time (with the addition of more storage and hosts) making them potentialy unstable. Devices can become unresponsive due to excessive LIP activity.

The issue can be recorded in multiple LOOP ONLINE/OFFLINE messages on the host (/var/adm/messages) and on rapidly increasing LIP counters on the switch ports (Captured by Explorer's capture.sparc output).

Resolution

If Private loop support is required (SL port mode) then create SL zones such that there are the minimum number of nodes/devices within that zone. By default there are no SL zones created. Creating SL zones that include just the hosts and storage devices that need to communicate, achieves multiple benefits:-

Devices in zone-B will not be affected by a device performing a LIP in zone-A.

Assists in keeping the 'solution' within the confines of the SL qualification limits - last updated in SAN 3.

Improves security, assists in preventing accidental access.

Diagnosing loop issues becomes easier, less devices are involved.

SAN 3 was the final development release of private loop support on 'SL' port modes on SUN/Qlogic 1G switches.

The limits of qualification at that time were:-

Sun StorEdge A5200 Array
Feature Supported
Cascading	No
Zone type	SL zone only
Maximum number of arrays per SL zone	3
Maximum initiators per SL zone	2
Maximum initiators per array	4(2 per loop)
Split loop support	No

While for the T3/T3+ array the corresponding values are

Sun StorEdge T3 Array and T3+ Array
Feature Supported
Cascading	Yes
Zone Type	nameserver zone, SL zone
Maximum number of arrays per zone	8
Maximum initiators per LUN	2
Maximum initiators per zone	2

see Publication 816-0830-12 dated October 2001 for more details.

Restriction: SL zones are setup at the port level. A port can only be in 1 SL zone, ie they cannot overlap.

Additional Information

It is outside the scope of this article to recommend 1 topology type over another (ie, fabric vs private-loop). However, if virtual private-loop support (SL) is required on the Sun 1G switch, then it should attempt to remain inside qualification limits.

Exceeding these limits _can_ cause loop instability, even on SANs where there are no marginal componenets. No such limitations apply in the 2G switches (or 1G switches with FW > 40233) , as they dont support SL ports.

Product
Sun StorageTek Network 1 Gb FC Switch-8
Sun StorageTek 1 GB 16-Port Switch

sanbox, SL, segmented, loop, unstable, LIP
Previously Published As
78489

Change History
Date: 2004-10-08
User Name: 25440
Action: Approved
Comment: Removed "Sanbox" from title as this is not Sun's product name (it's there in the keywords). Applied STM markup. Publishing
Version: 3
Date: 2004-10-08
User Name: 25440
Action: Accept
Comment:
Version: 0
Date: 2004-10-08
User Name: 92689
Action: Approved
Comment: Helpful document. No changes required.
Version: 0
Date: 2004-10-07
User Name: 92689
Action: Accept
Comment:
Version: 0
Date: 2004-10-04
User Name: 34660
Action: Approved
Comment: Comments welcomed.
Version: 0
Date: 2004-10-04
User Name: 34660
Action: Created
Comment:
Version: 0
Product_uuid
0e4a2a4f-d43b-11d8-ab52-080020a9ed93|Sun StorageTek Network 1 Gb FC Switch-8
ad1234c3-d43b-11d8-ab52-080020a9ed93|Sun StorageTek 1 GB 16-Port Switch

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