[CentOS] How do I know if I am using SAN?

John R Pierce pierce at hogranch.com
Thu Aug 23 00:01:03 UTC 2007


Mag Gam wrote:
> No, not trolling Tom. I am faily new to Linux, and was wondering how 
> can I verify if my Linux host is connected to a SAN? I want to know if 
> my disks (sfdisk -l) are local or attached to external storage (ie, 
> SAN). Also, how would I figure out parent and children relationships 
> between devices, especially HBA and their disks.

from the OS's perspective, there's not much difference between a 'SAN' 
disk and a direct connect disk other than the interface type.     a 
fiberchannel SAN vs a fiberchannel direct connect RAID differs only in 
that the fiberchannel SAN may be servicing multiple computers while the 
fiberchannel direct connect raid is only servicing this one system.

now, some folks consider any FC device to be SAN.     Having used 
directly connectted fiberchannel raid on Unix systems, I don't hold to this.


cat /proc/scsi/scsi will give you some info on what sort of stuff the 
SCSI system sees.

one system...

# cat /proc/scsi/scsi
Attached devices:
Host: scsi0 Channel: 00 Id: 00 Lun: 00
  Vendor: COMPAQ   Model: MSA1000          Rev: 4.32
  Type:   RAID                             ANSI SCSI revision: 04
Host: scsi0 Channel: 00 Id: 00 Lun: 01
  Vendor: COMPAQ   Model: MSA1000 VOLUME   Rev: 4.32
  Type:   Direct-Access                    ANSI SCSI revision: 04
Host: scsi0 Channel: 00 Id: 00 Lun: 02
  Vendor: COMPAQ   Model: MSA1000 VOLUME   Rev: 4.32
  Type:   Direct-Access                    ANSI SCSI revision: 04
Host: scsi0 Channel: 00 Id: 00 Lun: 03
  Vendor: COMPAQ   Model: MSA1000 VOLUME   Rev: 4.32
  Type:   Direct-Access                    ANSI SCSI revision: 04
Host: scsi0 Channel: 00 Id: 00 Lun: 07
  Vendor: COMPAQ   Model: MSA1000 VOLUME   Rev: 4.32
  Type:   Direct-Access



the HP MSA1000 could be used as a SAN or as a directly connected 
external RAID, the host simply can't see this without invoking MSA1000 
specific configuration software.

on another system...

# cat /proc/scsi/scsi
Attached devices:
Host: scsi0 Channel: 00 Id: 00 Lun: 00
  Vendor: IBM-ESXS Model: ST936701LC    FN Rev: B41D
  Type:   Direct-Access                    ANSI SCSI revision: 04
Host: scsi1 Channel: 00 Id: 00 Lun: 00
  Vendor: SUN      Model: StorEdge 3510    Rev: 415F
  Type:   Direct-Access                    ANSI SCSI revision: 03
Host: scsi1 Channel: 00 Id: 01 Lun: 00
  Vendor: SUN      Model: StorEdge 3510    Rev: 415F
  Type:   Enclosure                        ANSI SCSI revision: 03


scsi0 is a directly connected SCSI disk.    scsi1 is a logical unit on a 
Sun StorEdge 3510FC, which is another barely-a-SAN storage controller.   
The same thing applies, the only way I could tell this is a SAN would be 
to know that in fact there's a fiber switch (Qlogic SANbox) between the 
host (an IBM bladecenter HS20) and the 3510FC, and that there are other 
systems connected to the same 3510FC and using other volumes on it.




More information about the CentOS mailing list