I’ve blogged briefly about the MSA array before, thinking it was a reasonable piece of kit for the price, assuming your expectations were low. But I had a problem recently with a particular MSA2012fc and don’t know whether I’ve got it right or whether I’m missing something fundamental.<\/p>\n
I had it setup in a DAS configuration. Interconnect was turned on, and loop was the default topology in place.\u00a0 This worked fine for the 2 RHEL boxes attached to the host. Later I connected the array and 2 hosts to 2 Brocade 300 Switches with discrete fabrics. I changed the topology to point-to-point, and changed to straight-through from interconnect. This seemed like a reasonable thing to do based on my understanding of the admin, user and reference guides.<\/p>\n
In a switched topology \/ straight-through \/ point-to-point connection, LUNs owned by a vdisk on controller A are only presented via paths from controller A. If controller A fails however, I don’t believe the vdisk fails over. If, however, a cable or switch fails, you’re covered, because each controller is cabled to each fabric. I believe this is why I saw two paths to everything – these being the fibre ports of the controller owning the vdisk that owns the LUN.<\/p>\n
In a direct-attach \/ interconnect \/ loop setup, controllers mirror their peer’s LUNs via the higher ports, so Controller A presents paths to controller B’s LUNs via A1. In this setup, you could sustain a controller failure, as a vdisk would be presented via the peer.The problem with this, however, is that interconnect is never used in a switched environment. I don’t believe changing the ports to loop will help, nor would removing the switches.<\/p>\n
Have I totally missed the point here? Has anyone else seen this? Was there a workaround? Or something fixed in later revs of the code? It seems strange that HP would advertise this as an active-active array, but only for DAS configs.<\/p>\n","protected":false},"excerpt":{"rendered":"
I’ve blogged briefly about the MSA array before, thinking it was a reasonable piece of kit for the price, assuming your expectations were low. But I had a problem recently with a particular MSA2012fc and don’t know whether I’ve got it right or whether I’m missing something fundamental. I had it setup in a DAS […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[86,5],"tags":[132,797,87,40,787,133],"class_list":["post-217","post","type-post","status-publish","format-standard","hentry","category-hp","category-storage","tag-failover","tag-hp","tag-msa2000","tag-san","tag-storage","tag-topology"],"_links":{"self":[{"href":"https:\/\/www.penguinpunk.net\/blog\/wp-json\/wp\/v2\/posts\/217","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.penguinpunk.net\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.penguinpunk.net\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.penguinpunk.net\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.penguinpunk.net\/blog\/wp-json\/wp\/v2\/comments?post=217"}],"version-history":[{"count":3,"href":"https:\/\/www.penguinpunk.net\/blog\/wp-json\/wp\/v2\/posts\/217\/revisions"}],"predecessor-version":[{"id":223,"href":"https:\/\/www.penguinpunk.net\/blog\/wp-json\/wp\/v2\/posts\/217\/revisions\/223"}],"wp:attachment":[{"href":"https:\/\/www.penguinpunk.net\/blog\/wp-json\/wp\/v2\/media?parent=217"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.penguinpunk.net\/blog\/wp-json\/wp\/v2\/categories?post=217"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.penguinpunk.net\/blog\/wp-json\/wp\/v2\/tags?post=217"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}