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SAN 101

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Sep 29, 2008
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we are looking to implement a san at work and i need a san 101 introduction and information to read up on in order to start t o spec one out. can you provide some help or links for information? thanks.
 
Have a look at the Netapp, EMC, LeftHand\HP and Nexsan sites for some of the players in prebuilt SANs. Don't forget that the likes of Dell and IBM also offer SAN solutions.

If you're planning on building your own then have a look at Openfiler.

You need to decide however if you're going down the route of FC or iSCSI (FC is way more expensive), whether you need to get hardware iSCSI initiators or can get away with software ones.

There is a lot out there, they aren't cheap and really aren't something that you can just get into.



Simon

The real world is not about exam scores, it's about ability.

 
For a good general overview go to the SNIA website discuss SAN standards Good freebie SAN technology guides can be also obtained from the IBM redbooks site (although they are geared to IBM technology the concepts are the same)

In terms of iSCSI vs FC; general rule.. if you don't already have a fiber based infrastructure already in place, it would be a lot cheaper to go the iSCSI route
 
Thanks for the replies. I will check the ibm redbook to get some reading done. I currently do not have a fiber infrastructure. what is the price difference? double? what do i need to implement a san? do i need to move into a blade environment as well? right now i just have nas and servers all over the place. thank you.
 
I would say more than double but I have never worked with FC, just seen the price of the kit.

As far as servers go, you can still use your old rack mounted ones, ideally with a hardware iSCSI initiator card.

I think what might be a good idea is to explain what it is you're trying to do.

Simon

The real world is not about exam scores, it's about ability.

 
Fiber Channel is a lot more expensive than iSCSI and probably doesn't make sense for most people to use unless you have a large bandwidth requirement for your disks.
 
My enviroment is solely Fiber and for a quick answer... yes fiber is more expensive than iscsi. If just starting out with a san and high performance is not a must than stick with iscsi, save the budget. If you plan on running services like virtualization, exchange, sql, or VDI than fiber may be the way to go. Personally I stick with fiber simply because we already have the infrastructure in place and paid for the HBA's and controllers, Also... the technology if proven and has been around for a long time compared to iscsi which is IP based and and (in my opinion) not as reliable as FC. BUT, If I was starting fresh I would seriuosly consider iscsi, the technology is constantly being approved and like I stated before, its cheaper.

John Sorensen
Network/Systems Admin
 
We're starting to see customers who have FC SANs but I'm getting the idea that some of them really don't understand very well what they're good at and what they're not. We're seeing them take our database apps and configure the data drives to be on the SAN-- but that means a lot of little disk I/O transactions over the connection during queries, etc. And this is going to a centralized FC SAN that is being shared by just about everything-- dozens of servers at least.

It's my understanding that FC SANS may have great transfer rates, but their LATENCY may not be all that great. Is that correct? On the other hand, if we have a multi-server datawarehouse app, using FC to move multi-gigabyte database files from one server to the next might be a pretty good scheme. But this is all pretty new to me. Ignoring latency for the time being, are FC transfer rates better than locally attached disk drives? If so, I would think this is simply because FC transfer rate is better than SATA. Customers are deciding to go to SAN without talking to us, and some of our apps are seriously disk-bound because of the database operations. But I can't hit them with a clue stick until I become a little less ignorant about it myself...
 
SAN disk performance depends on many factors. Like wether the disks are SAS or SCSI, the disk speed, the spindle count, Raid level, and the amount of LUNs/Arrays. If for example you have a database, 300 GB in size, having 6 x 146 15k SFF SAS drives in a raid 10 connect via 4G FC would give you optimum performance and fualt tolerance that would rival any local storage. Plus with local storage is limited by slots and most newer SAN units are expandable to rediculous sizes plus newer SAN solution have many nice features like snapshots, deduplication, virtualization, and more.

John Sorensen
Network/Systems Admin
 
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