On Feb 26, 2009, at 12:28 AM, Wojciech Puchar wrote:

FreeBSD services.tcbug.org 8.0-CURRENT FreeBSD 8.0-CURRENT #0: Mon Feb 16 21:07:14 UTC 2009 root@:/usr/obj/usr/src/sys/SERVICES amd64

But 6.x and 7.x give similar results.

The disks themselves are capable of sequential read/write in the 180 Meg/sec range, so I'm trying to understand why I'm being told they are 100 Meg/sec, and why that seems to be their real world performance cap.


probably you use RAID5


Hrmm, I should have included drive configuration.

r...@services /home/jpaetzel ->tw_cli /c0 show

Unit UnitType Status %RCmpl %V/I/M Stripe Size(GB) Cache AVrfy
------------------------------------------------------------------------------
u0 RAID-1 OK - - - 135.031 ON ON u1 RAID-1 OK - - - 298.013 ON ON

VPort Status         Unit Size      Type  Phy Encl-Slot    Model
------------------------------------------------------------------------------
p0 OK u0 136.98 GB SAS 0 - FUJITSU MBA3147RC p1 OK u0 136.98 GB SAS 1 - FUJITSU MBA3147RC p2 OK u1 298.09 GB SATA 2 - WDC WD3200AAKS-00SB p3 OK u1 298.09 GB SATA 3 - WDC WD3200AAKS-00SB


But I get similar results when I connect just a single SAS drive and export it as a raw device. It's also worth noting that the SATA drive array is reported as 100MB/sec transfers, even though the drives aren't capable of anything close to that, unless they are reading from cache, in which case SATA2 is capable of more like 300MB/sec...but then so is SAS...


Thanks,

Josh Paetzel




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