# SCSI woks very slow



## Dr_Phoenix (Jun 1, 2009)

Hi for all! 
I have a server:

```
[B]OS[/B]: FreeBSD 6.3-RELEASE
[B]CPU[/B]: 2x Intel(R) Xeon(TM) 3.06GHz Logical CPUs per core: 2
[B]RAM[/B] : real memory  = 4026466304 (3839 MB)
[B]SCSI[/B]: ahd0 <Adaptec AIC7901A Ultra320 SCSI adapter> port 0x2000-0x20ff,0x2400-0x24ff mem 0xfeaf0000-0xfeaf1fff irq 26 at device 3.0 on pci3
[B]DISKS[/B]:
da0 at ahd0 bus 0 target 0 lun 0
da0: <MAXTOR ATLAS10K4_73SCA DFV0> Fixed Direct Access SCSI-3 device
da0: 320.000MB/s transfers (160.000MHz, offset 127, 16bit), Tagged Queueing Enabled
da0: 70149MB (143666192 512 byte sectors: 255H 63S/T 8942C)
da1 at ahd0 bus 0 target 1 lun 0
da1: <FUJITSU MAT3073NC 0105> Fixed Direct Access SCSI-3 device
da1: 320.000MB/s transfers (160.000MHz, offset 127, 16bit), Tagged Queueing Enabled
da1: 70136MB (143638992 512 byte sectors: 255H 63S/T 8941C)

[B]Additional scsi info[/B]:
machine# camcontrol devlist
<MAXTOR ATLAS10K4_73SCA DFV0>      at scbus0 target 0 lun 0 (pass0,da0)
<FUJITSU MAT3073NC 0105>           at scbus0 target 1 lun 0 (pass1,da1)
<ESG-SHV SCA HSBP M15 0.11>        at scbus0 target 6 lun 0 (ses0,pass2)
```

Scsi works very slow, testing usin direct read from disk using dd:

```
machine# dd if=/dev/da0 of=/dev/null
^C203387+0 records in
203387+0 records out
104134144 bytes transferred in 47.948925 secs (2171772 bytes/sec)
```

Result: 2Mb/sec direct read speed, on other my servers with different controllers this value is 7-9Mb/sec!
I am using firebird DB engine and it works very slow, to select some data from 3Gb database I need to wait 1-2 hour, on other servers it takes 10-15 minutes...

Somebody can help me or explain what is the problem...?
Thanks for All !


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## brd@ (Jun 1, 2009)

Can you test with 7.2? I seem to recall a bug in the SCSI subsystem that crept in before then. Sorry I can't be more specific, that is all I remember.


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