Veritas, EMC, and luns

brownwrap

I had an interview the other day and several things came up that I have had exposure to, but am not an expert on. I have set up RAIDs with the help of customer support, but don't fully understand the idea of LUNs. As I recall I think they were setup so that some servers had access to what I will call a partition, while other servers could not access that partition. This was all done through QLogic fiber channel boards and the RAIDs had a FC interface. I'm guessing this is a SAN setup.

We had lots and lots of diferent kinds of storage at the last place I worked at. We had two NetApps devices, one an R200 with 50 terabytes, the other unit had just came in when I was leaving, but it help another 100 TB. Anyway I have never worked with EMC, but this new job has EMC equipment. A while back someone posted info on EMC certs. This place has a storage group so my involvement might be minimal, since I would be working as an Unix Administrator.

Finally, the last subject that came up was the Veritas filesystem. We actually have Veritas where I am at now, but I have never had to touch it. I did a brief web search on these topics and read a little about Veritas. What is so unique about it. We use it for our database, but I have worked other places with an Oracle database and it didn't require Veritas.

Just trying to get a heads-up on some of this.

sidsanders

quick ref: Logical Unit Number - Wikipedia, the free encyclopedia

lun can be a disk, tape, tape changer (robot arm), dvd device, etc. some of what you are talking about is lun masking, and perhaps fc zoning. lun masking is allowing an initiator (client machine you can say) see certain luns presented from a target (~ server, EMC would be the target) and not to any/all other initiators. emc uses storage groups to present luns to a host (or more than 1 for a cluster). fc zoning will allow the initiator to see a specific target -- note the target is then doing the authorization of what the initiator (client) can see. so the 2 items together are how a san will attempt to make things work without corrupting everyone's disk file systems.

zoning -- lets an initiator see a target
lun masking -- allows an initiator access to certain luns provided by the target

vxfs, is a journaling file system. that is it uses a log to track fs changes. when machines go nutty, vxfs slices can recover faster than ufs/ext style fs's. vxfs also has in most cases: larger disk support, better inode support, advanced i/o features for db's, clustered version of vxfs, etc. vxfs isnt the only journaling fs out there however its one of the few that you will see on a few diff plats compared to ibm's jfs/jfs2.

brownwrap

sidsanders wrote: »

quick ref: Logical Unit Number - Wikipedia, the free encyclopedia

lun can be a disk, tape, tape changer (robot arm), dvd device, etc. some of what you are talking about is lun masking, and perhaps fc zoning. lun masking is allowing an initiator (client machine you can say) see certain luns presented from a target (~ server, EMC would be the target) and not to any/all other initiators. emc uses storage groups to present luns to a host (or more than 1 for a cluster). fc zoning will allow the initiator to see a specific target -- note the target is then doing the authorization of what the initiator (client) can see. so the 2 items together are how a san will attempt to make things work without corrupting everyone's disk file systems.

zoning -- lets an initiator see a target
lun masking -- allows an initiator access to certain luns provided by the target

vxfs, is a journaling file system. that is it uses a log to track fs changes. when machines go nutty, vxfs slices can recover faster than ufs/ext style fs's. vxfs also has in most cases: larger disk support, better inode support, advanced i/o features for db's, clustered version of vxfs, etc. vxfs isnt the only journaling fs out there however its one of the few that you will see on a few diff plats compared to ibm's jfs/jfs2.

I don't know if I will land this job, but I can see there is a lot to learn.