Re: Dell SAS5 Performance Issue



Richard Tector wrote:
I'm suffering from very slow write performance on a Dell PowerEdge 860
with the SAS5/IR controller (mpt driver) running either 6.2-RELEASE or
6.2-STABLE with sources from yesterday. The controller hosts 2 Western
Digital 320GB SATA disks in a RAID1 configuration.
Reads approach 65MB/s however writes appear extremely slow, in the
region of 6-7MB/s with a dd and a blocksize of 1MB all the way down to
about 300KB/s while extracting a ports snapshot.

It was suggested to me that perhaps write caching has been disabled on
the controller however no options exist within the BIOS configuration to
view/adjust *any* caching options.

You looked in the controller's BIOS, not motherboard's, right? There
should be at least a "write through" vs "write back" switch...
If you don't have a battery for the SAS controller, get one.

Has anyone else experienced this issue?

No, but can you post the relevant bits for the controller from dmesg?


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Relevant Pages

  • Re: Dell SAS5 Performance Issue
    ... On 3/27/07, Richard Tector wrote: ... The controller hosts 2 Western ... It was suggested to me that perhaps write caching has been disabled on ... view/adjust *any* caching options. ...
    (freebsd-stable)
  • Re: Dell SAS5 Performance Issue
    ... On 3/27/07, Richard Tector wrote: ... The controller hosts 2 Western ... It was suggested to me that perhaps write caching has been disabled on ... view/adjust *any* caching options. ...
    (freebsd-stable)
  • Dell SAS5 Performance Issue
    ... I'm suffering from very slow write performance on a Dell PowerEdge 860 with the SAS5/IR controller running either 6.2-RELEASE or 6.2-STABLE with sources from yesterday. ... The controller hosts 2 Western Digital 320GB SATA disks in a RAID1 configuration. ... It was suggested to me that perhaps write caching has been disabled on the controller however no options exist within the BIOS configuration to view/adjust *any* caching options. ...
    (freebsd-stable)