Comments on: san consideration for backup: hba

By: kdanik

kdanik — Wed, 25 Jan 2006 16:49:59 +0000

You do NOT want to use the same hba to access both tape and disk. That being said — you also do NOT want to have tape and disk in the same zone. That is, if you want to prevent a lot of headaches This is best practices and what I tell any customer I visit (I’ve seen way too many errors generated and if you want more technical details, I’d be happy to explain more.)

Best practice:
If you’re looking for redundancy, dual hba’s w/ dual ports (port fails, or hba fails you’re covered), dual paths to your switches/storage, obviously dual sans and redundant arrays. It all depends on what you’re trying to do.

Bottom line — don’t mix tape/disk on the same hba or in the same zone.

By: dcsys99

dcsys99 — Mon, 23 Jan 2006 07:49:10 +0000

Powerpath does not necessarily require a second adapter, but it is designed to give failover and load balancing. A second adapter will be needed to accomplish this. If you only have one adapter, Powerpath may do a little tweaking of the adapter, but not much. I still recommend a second adapter.

By: veritatis

veritatis — Sun, 22 Jan 2006 21:34:48 +0000

Hi all,

Thank you all for taking time to answer. Here are additional info:
Ths O/S would be RedHat ES 3. Yes, failover software (from EMC since the disk storage is EMC) would be used and the bandwidth of the pipe is 2GB, the tape drive is fibre based LTO3.
The backups, definitely, would be scheduled off hours.
Mcdata switch will be used. Hope there’s an equivalent SAN Health utility for McData.

Thanks.

By: carrollthomas

carrollthomas — Sat, 21 Jan 2006 13:22:13 +0000

I would not seperate disk and tape as you will loose locality and potneitally add delay to your backups and if you lost and ISL (inter switch link) you will be unable to backup up at all. Usig the Brocade San Health is a good idea, it’s free and it gives you loads of great info including their analysis of your fabric layout etc..

By: s00032

s00032 — Sat, 21 Jan 2006 07:11:27 +0000

Well if you can live with the performance and you are using a scsi-3 driver. The scsi-3 driver will (if needed) do in reset instead of target resets. The target resets can interfere with your tape access and become critical for the tape access. (STORport driver for Windows 2003 is a scsi-3 driver as a example).

By: chriswible

chriswible — Fri, 20 Jan 2006 15:42:55 +0000

In my experience I have seen using the same HBA for disk and tape access cause problems on the tape access side, making backups fail. I would, and do, use a different HBA for the tape access. I would also consider totally separating the disk and tape SAN’s (separate switches).

By: stormenterprises

stormenterprises — Fri, 20 Jan 2006 12:27:47 +0000

Can 1 hba be used to access disk storage and tape devices on a SAN? Is this a good practice?

Yes, you can use 1 hba to run your backups.

No, it is not wise to do so. It really depends on how robust your systems are. Are you using failover? Do you have another hbs that can be used in emergency situations? Do the backups run into production time? Is the hba you are using also the production hba? How importanta is it that your backups run at the scheduled time, and only at that time? How reliable is your hba?

There are a number of questions you need to answer before you make the decisions you asked. Good Luck

By: martoncik

martoncik — Fri, 20 Jan 2006 09:30:12 +0000

Depends on the size of your SAN. Brocade has a good free tool called SAN Health that will analyze your SAN and do a full report with a Visio diagram included. It is recommended that you have 2 hbas.

By: carrollthomas

carrollthomas — Fri, 20 Jan 2006 07:22:36 +0000

It depends on your san infrastructure, are you using failover software like MPIO or Secure Path, what is you O/S type, and most importantly what is the bandwidth of your pipe, are you using 1GB or 2GB hba’s do you use persistant bind etc.

I would recommend that if you are using a failover application like MPIO and you do have 2 hba’s in a server then using 1 hba for backup and san access is acceptable. You need to do a full diagram and check the max/min i/o you get from both your tape drive and san.

Is your tape drive fibre or scsi based.

The more info you can supply me the better I can answer and guide you.

Regards

Thomas
BCSD BCFP