04-19-2016 09:34 AM
Hello Guys,
I have one HBA (Dual-port) on my media server. 4gb/s speed set on each port.
One port of this HBA is zoned with 12 LTO5 Tape-drives. Another port of the Same HBA is free.
Can i zone 6 drives on one port and another 6 drives on other port on the same HBA ?
This way i can feed 4+4=8 gb/sec traffic simultaneously to my san switch instead of sending 4gb/sec speed to 12 drives.
Is it good idea ? OR bad ? Any thought ? Please comment with suggestions.
04-19-2016 09:53 AM
Its a good idea. I would zone all 12 drives to both ports through different switches(if available). This way in case of port/SFP/Switch/cable failure on one port/path we have another port already configured to all backup to all 12 drives. Please remember that NBU uses single path to communicate with tape drive but can identify all paths available. You can make sure that the current path used balances the FC traffic.
04-19-2016 09:57 AM
Good lord, man - just be sure not to try to drive 12 LTO5 drives over a single dual-port HBA!
But yeah - you should split your traffic over both ports. And do it the way SymGuy suggests. Load-balancing/redundancy = GOOD.
04-19-2016 10:06 AM
Hello SymGuy,
Its single qlogic HBA-card with dual ports (4 gb/sec speed on each port). Both ports are connected to single san-switch and from there 12 drives are zoned .
Are you suggesting zoning of all 12 drives from both hba-ports of a single HBA card.
Will it work for all backup-softwares available (example,EMC Networker,TSM,Comvault) or specific to Netbackup only ?
Will this configration actually feed more data (4+4=8gb/sec) to san-switch simultaneously so that drives can receive speedy data flow rate to write ?
04-19-2016 11:10 AM
I would zone 6 tape drives to each port, especially as I have been told that Netbackup does not support dual data paths for tape drives.
See https://www.veritas.com/support/en_US/article.000021124 for more information.
Think the only way for this to work is if the tape drive driver creates pseudo devices, so the devices stay the same regardless of the SAN path, but have not seen any drivers like that.
https://www.veritas.com/support/en_US/article.000076423 might be worth a read too
Also the planning and performance tunning guide, have some stuff about adapters and how to disperse the load for the best performance
Must say I am curious to what input device(s) is on this server
To really have a speedy data flow rate, you will have to more HBA's maybe even more servers as the internal IO busses often end up being the bottleneck even talking enteprise tape drives like LTO5
04-19-2016 10:15 PM
Thanks Michael,
Hello Guys,
I want more suggestions, inputs. Please provide expertise thoughts.
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s single qlogic HBA-card with dual ports (4 gb/sec speed on each port). Both ports are connected to single san-switch and from there 12 drives are zoned .
Are you suggesting zoning of all 12 drives from both hba-ports of a single HBA card.
Will it work for all backup-softwares available (example,EMC Networker,TSM,Comvault) or specific to Netbackup only ?
Will this configration actually feed more data (4+4=8gb/sec) to san-switch simultaneously so that drives can receive speedy data flow rate to write ?
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04-25-2016 11:26 PM
Hello Guys,
I want more suggestions, inputs. Please provide expertise thoughts.Suggestions :)
I am waiting.
04-26-2016 12:02 AM
This guide covers how to size the number of HBA ports and tape drives:
Symantec NetBackup Backup Planning and Performance Tuning Guide Release 7.5 and Release 7.6
December 14, 2015
http://www.veritas.com/docs/000004178
04-26-2016 12:09 AM
1) single qlogic HBA-card with dual ports (4 gb/sec speed on each port). Both ports are connected to single san-switch and from there 12 drives are zoned .
Seems like a lot of tape drives for just two HBA ports.
2) Are you suggesting zoning of all 12 drives from both hba-ports of a single HBA card.
I don't think anyone was suggesting that this is a good thing to do, only that it might be the only thing that you can do, given your limited HBA port resources.
3) Will it work for all backup-softwares available (example,EMC Networker,TSM,Comvault) or specific to Netbackup only ?
You can certainly present in this way to pretty much any backup software. But will it work? In practice probably not. I mean it may appear to work, but, IMO, two HBA ports is not enough for 12 tape drives.
4) Will this configration actually feed more data (4+4=8gb/sec) to san-switch simultaneously so that drives can receive speedy data flow rate to write ?
Yes, you should be able to drive both server HBA ports at 4Gb/s. But is that enough to make six LTO5 tape drives all operate in streaming mode? No, I doubt it.
.
Take your time to work through the planning and performance guide, and you'll see why.
.
5) It's one thing to have 12 tape drives at the back-end, but is the server capable of receiving enough data, AND capable of "moving" enough data? I mean, does the server have enough LAN/SAN ingest bandwidth? Does the server have enough "backplane/motherboard/PCIe" bandwidth to actually move enough data across the internal "buses" to be able to stream 12 tape drives. Probably not.
04-26-2016 12:42 AM
HBA port = 4gb/sec is approx 400MB/s (if you divide by 10, this allow for overheads, so is actually about right, as opposed to being mathamatically correct and dividing by 8).
The max spped of an LTO5 drive is about 140MB/s so therefore a 4gb port should have no more than 400/140 drives attached.
400/140 = 2.85
To allow the 'system' to be able to write to each drive simultaniously at around maximum speed you should have no more than x2 or 3 LTO5 drives per 4Gb port.
x6 drives on the port, if run at the same time allows only a max through put to each drive of 400/6 = 66MB/s
The minimum streaming speed for LTO5 is about 60MB/s if the data is uncompressed. If the data is compressable the min streaming speed increases. Allowing the drives to run below the minimum streaming speed will cause 'shoe shining' which damages both the tapes and drives. With x6 drives per 4Gb port, you are almost certainly going to cause shoe shining.
My view is that 6 drives per port would demonstrate bad system design will potentially cause you serious problems that cannot be worked around.