Ask about boot from SAN

Question

I alreary read a lot of document about boot from SAN solution of DELL but i dont know how to do to boot from SAN . Who have exprience about boot from SAN , please tell me something following : - How to create boot device ? Can i mirror the local disk of server or using a software to create a boot device ? - Which software was need to boot from SAN ? - How do admin do to update the access righ on the RAID ports to reflec the change in the WWN of the replacement HBA ?

Dev Mgr · Answer

Boot from SAN is pretty complicated and has several limitations.

First off, what kind of SAN are you wanting to boot to? Not all SANs support boot-from-SAN.

Also, which OS are you intending to use (including SP/kernel version/level)?

There are a few limitations to boot from SAN as well.

In my opinion booting from (mirrored) internal SCSI drives in a server is a whole lot easier to manage. If you're concerned about a situation where the server itself (mobo, cpu, memory, etc) completely fails, then just move the 2 mirrored drives to the stand-by server and boot it up. If it's set up properly, this process will take you maybe 10 minutes, where complications with boot-from-san can take hours to fix. And 'OS-corruption-risk' isn't a reason to go to boot from SAN, as it can happen on a SAN drive as well.

If you want to go ahead and do boot-from-san, I'd highly recommend contacting Dell sales and buying an installation to get it done by professionals who know how to do this, or have access to tools that outline how to do it correctly.

Bowlj001 · Answer

We have been booting from SAN for several years and absolutely think it’s the best approach for us - (For DR purposes and we don’t have to manage any local disk.)

There isn’t anything that designates a boot LUN specifically. We just create ~2-3 10GB LUNS per each physical for our systems. Basically, you need to monitor IO just like any other lun. If you do a lot of paging or reboot your servers often, then you may wish to distribute your LUNs accordingly. The rest of the drive space is basically allocated for Data.

Other than that, you need to configure your HBA to boot from SAN. We use both Emulex and Qlogic cards and they both work just fine.

High-Level Steps for a Clariion System:
#1. Connect and zone your HBA to your SAN system
#2. In Navisphere, in Connectivity Status, you will eventually see your HBA WWN
      (May have to do an “Update Now” a few times for the WWN to appear, but as long as the HBA logs into the switch and is zoned properly, it will eventually appear.)
#3. Manually register your HBA information via Connectivity Status window
#4. Bind a new LUN used for booting your server (if needed)
#4. Create a Storage Group and assign the new Registered Host and Boot LUN
#5. Configure the HBA to boot from SAN
           Emulex: Boot into configuration and select “Configure Boot Devices”
                         In Configure Primary Device ensure you enter LUN 00 and Point-to-
                         point (WWPN)

#6. Reboot system and load operating system…

If you have to replace an HBA, then you just need to rezone and register the new HBA. Data is never destroyed unless there is some kind of data corruption due to the outage (we have never encountered such an issue – knock on wood.)

trancompany · Answer

Thank for answer for yours .  Torrorow , i read some documents and alreary knew how to create LUN with RAID port and HBA's WWN and change it to be boot device but i still dont know how to load OS to that LUN .  Can you tell me some method to load OS to the boot device ? For example : mirror from MirrorView , clone from SnapView or install OS just like the local disk .

Bowlj001 · Answer

For Windows, you install the OS like you would for any other server (CD, PXE, etc.) Press F6 during the installation process so that you can load the proper SCSI drivers and you are off and running.   Page 18 of the following pdf guide describes the process for an Emulex HBA. QLogic has a similar guide on their web site as well.   http://www.emulex.com/ts/downloads/shared_docs/ub/501a9_sun/ubupdate.pdf   Good luck.

trancompany · Answer

Thank Bowlj001 , i alreary read the document that you sent to me . But there are only the guide to create a new boot LUN . I dont know whether you know how to create a boot LUN from the local disk . For example : in my company , we have a SAN system , there are two PE6600 in SAN and PE6600 have local disk to boot . Now , we want to create a LUN on storage system that just like the local disk , that mean when having a failure at PE6600 we can replace it by other PE6600 and using the LUN on storage system . Can i use the mirror or clone to do it ?

Bowlj001 · Answer

I believe you are trying to keep a copy of your current boot drives (locally attached drives) on the SAN for DR purposes?  If the 6600 goes down, you would like to boot from the SAN and resume operations?   One of the biggest problems you will have is overcoming the differences between booting from SAN via an HBA and booting locally via a SCSI RAID controller.  Windows will have a very hard time booting from SAN with a mirror copy of your local disk as you will have many registry changes, boot.ini differences, scsi driver differences, etc.   Other DR options to consider:   - Mirror your local drives and have a good backup (including the System State)   - Clustering the two servers.  This way, if you loose either of your 6600's you are covered as long as your application(s) are cluster aware.   - Boot from SAN to begin with.  You just need to rezone if you loose an HBA or move the LUN to another server.   - Use Bare Metal Restore option such as Veritas Netbackup to restore an image to different hardware.   Hope this helps a little. Sorry if I've missed your question completely.

trancompany · Answer

Thank Bowlj001

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