Re: [Networker] SAN Tape Drive / Storage / Host Connectivity

I don't know about Microsoft but I found reference to this in the IBM Ultium
Device Drivers Installation and Users Guide.

ftp://ftp.software.ibm.com/storage/devdrvr/Doc/IBM_ultrium_tape_IUG.pdf

There is a note in Chapter 29 on page 146 which reads:

Using a single Fibre Channel host bus adapter (HBA) for concurrent tape and
disk operations is not recommended. Tape and disk devices require
incompatible HBA settings for reliable operation and optimal performance
characteristics. Under stress conditions (high I/O rates for tape, disk, or
both)
where disk and tape subsystems share a common HBA, stability problems have
been observed. These issues are resolved by separating disk and tape I/O
streams onto separate HBAs and using SAN zoning to minimize contention.
IBM is focused on assuring server and storage configuration interoperability.
It
strongly recommends that your implementation plan includes provisions for
separating disk and tape workloads.

FYI,
Jon

Björn Lundström wrote:

> Hi,
>
> Interesting!
>
> Can you give me a pointer to where Microsoft states that
> the don´t support disk and tape on the same HBA ?
>
> I would be interested to read that document.
>
> ///Björn
>
> -----Original Message-----
> From: Willeat, Todd [mailto:TWilleat AT MHP.SMHS DOT COM]
> Sent: den 8 april 2003 20:35
> To: NETWORKER AT LISTMAIL.TEMPLE DOT EDU
> Subject: Re: [Networker] SAN Tape Drive / Storage / Host Connectivity
>
> It should be OK to have disk and tape on the same SAN. Microsoft does NOT
> support disk and tape on the same HBA - not that it won't work, but they
> don't recommend or support it. I'm not sure about the other OSs...
>
> -----Original Message-----
> From: Chris Madden [mailto:maddenca AT MYREALBOX DOT COM]
> Sent: Tuesday, April 08, 2003 11:18 AM
> To: NETWORKER AT LISTMAIL.TEMPLE DOT EDU
> Subject: [Networker] SAN Tape Drive / Storage / Host Connectivity
>
> I have a SAN in production for disk access and we are looking at adding
> fibre tape drives to the setup, initially driving these devices from a
> single storage node and thereafter doing LAN-free backups (i.e. installing
> additional storage nodes) on some larger hosts over time.  Today I have 2
> distinct SANs which are mirror copies of each other for availability, and
> have zoning implemented so that only hosts of a given OS type can see each
> other and their storage ports.  Tech environment includes: IBM ESSs, AIX,
> Solaris, Win2k, Netware, and coming soon 6 x IBM 3590H and 6 x IBM LTO-2
> drives.
>
> In order to add tape devices to the SAN I have some questions:
>
> 1) Is it wise to mix disk and tape on the same SAN?  My initial reaction is
> why not if you zone correctly, but perhaps there are other issues?
>
> 2) Can the HBAs in our hosts be used for both disk and tape access?  Again,
> my initial reaction is why not but perhaps there are other issues?  Is the
> answer different for each OS and if so which are OK and which not?
>
> I would prefer to share as much infrastructure between disk and tape as
> possible and I suspect with proper zoning the same fabric can be used for
> tape and disk.  If the case is however that I can't share the existing HBAs
> and need to add a 3rd HBA for tape use I have to pick which SAN (A or B) to
> plug it into, or I have to add a 4th HBA to get visibility to all the
> drives.  At that point the complexity (i.e some drives/hosts on one SAN and
> some on the other) suggests leaving SAN A and SAN B in place for disk, and
> creating a SAN C for tapes.  Creating SAN C however has significant costs
> (more switches, more HBAs) and would need good justification.
>
> Fellow NetWorkers, what would you do in my shoes?
>
> Kind Regards,
> Chris
>
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--
Jon Hickmott - jonny AT uwo DOT ca - NSC211c - (519) 661-2111x86025
Unix/Database administrator - ITS - UWO

"There are only 10 kinds of people in the world --
   Those who understand binary, and those who don't."

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