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One SAS drive reporting lower transfer rate

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rocru
Occasional Contributor

One SAS drive reporting lower transfer rate

Configuration:

 

P2000 LFF scaled down to two (2) D2600 in a daisy. All slots (36) filled with Seagate (HPs) ST3450857SS 450GB 15k SAS DP drives. Each port on the dual port controller is capable of 6Gb/ps transfer rate, however....

 

One drive (out of the 36) is reporting a 3.0Gb/ps transfer rate; reporting found using the P2000 SMU.

 

Why would the one drive report a lower transfer rate? 

 

I presummed a port failure, but the drive should still push 6.0Gb/ps.

 

Additionally, am I correct to assume that if one (1) drive, in a 12 drive RAID LUN, is transfering half of the data, the entire LUN will suffer?

 

 

3 REPLIES
AnkitM
Trusted Contributor
Solution

Re: One SAS drive reporting lower transfer rate

Drive changing speed from 6 Gbps to 3 Gbps is normal and expected. This has been documented; the following is from page 109 of the SMU Reference Guide

 

“Transfer Rate. The data transfer rate in Gbit per second.


Some 6-Gbps disks might not consistently support a 6-Gbps transfer rate. If this happens, the P2000 controller automatically adjusts transfers to those disks to 3 Gbps, increasing reliability and reducing error messages with little impact on system performance. This rate adjustment persists until the controller is restarted or power-cycled.”

 

HP P2000 G3 MSA System SMU Reference Guide :http://bizsupport2.austin.hp.com/bc/docs/support/SupportManual/c02520791/c02520791.pdf
Part number: 500911-008
First edition: February 2013

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rocru
Occasional Contributor

Re: One SAS drive reporting lower transfer rate

Thanks AnkitM

AnkitM
Trusted Contributor

Re: One SAS drive reporting lower transfer rate

You're welcome.

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