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New Contributor
Posts: 4
Registered: ‎01-14-2014

query about port speed,

hello

 

scenario:server HBA port supports 4g and current speed 4gps and My tapedrive current speed 8gbps.i have mapped this drive(8gbps)with server hba(4gbps).

 

my question here what is the maximum data rate transfering?4gbps or 8gbps?

what is the best practice to utilize the max speed from both ends.

 

Valued Contributor
Posts: 547
Registered: ‎03-20-2011

Re: query about port speed,

hi, the HBA will be running at 4Gb and the tape will be running at 8Gb. it will be OK when writing to the tape. however, when reading from the tape (restore, verification, duplication etc...) you are likely to run into the problems, especially if these ports are on the different switches and use ISL inbetween, or your switch is multi-ASIC and the devices are connected to different ASICs. i'd advise you turn on the bottleneck detection and monitor.

Regular Contributor
Posts: 161
Registered: ‎12-30-2009

Re: query about port speed,

[ Edited ]

From stated server to tape you'll get 4Gbps as the HBA is the limiting factor on bandwith.

Not that it really matters because the fasted tapedrives LTO6/T10000D are currently unable to fully utilize that BW at sustained rates.

LTO6 does 160MB/s > roughly 1.6Gbps

T10KD does 250 MB/s > roughly 2.5Gbps

 

Best practice means to do whatever is necessarry to keep tapedrives in streaming mode.

If tapedrives start to "shoeshine" you'll introduce additional wear on drive mechanisms, heads and tapecartridge itself.

 

New Contributor
Posts: 4
Registered: ‎01-14-2014

Re: query about port speed,

hi alexey,

 

how  turn on the bottleneck detection and monitor in the direcror switches.

 

here the switch model

switchType:     77.3
switchId:       fffc01

 

 

Frequent Contributor
Posts: 80
Registered: ‎01-28-2010

Re: query about port speed,

[ Edited ]

the command is

 

bottleneckmon --enable -alert

 

but before you execute the command, have a look at the help and/or doku for bottleneckmon.

 

if your switch or director is a older one, perma running bottleneckmon, can lead to traffic disruption.

 

http://www.brocade.com/downloads/documents/html_product_manuals/NA_SAN_1130/wwhelp/wwhimpl/common/html/wwhelp.htm#context=BNA_SAN_v1130&file=Ch_Performance.31.7.html

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