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kuhazor 02-25-2009 04:19 PM

SCSI device naming
 
Hi there,

I have this run a way problem with RHEL5. I am mounting and unmounting volumes from SAN. Let's say I mount volume A it becomes device /dev/sda volume B becomes /dev/sdb etc... Now if I remove volumes /dev/sda and /dev/sdb and map another volume C it becomes /dev/dbc. The problem here is that /dev/sda and /dev/sdb won't get recycled and soon I will be at /dev/sdx. Is there anyway to tell the OS to discard the no longer available devices and recycle the device names?

cat /proc/partitions

shows up the devices and might be the reason why I get new device name every time i map something new to the server.

/dev/sda
/dev/sdb

I have not rebooted the system and prefer not to. Any ideas anyone?

stress_junkie 02-25-2009 04:39 PM

Are you saying that the second time you mount volume A it isn't mapped as /dev/sda? If that is the case then you can make HAL rules to map a specific device to a specific mapping. You can use various criteria such as the UID number or a manufacturer's name.

Search this web site for more information about creating HAL rules.

kuhazor 02-25-2009 04:41 PM

No, if I map it the second time (i.e. every boot) this works fine i.e. it gets the same device name everytime. It is just that the old device names never expire or go away even if the volumes are long time ago removed..... I will check on the HAL rules. Thanks.

kuhazor 02-25-2009 06:41 PM

Well, something is getting cached including the volume sizes for these devices. I deleted one volume, created another and assigned the same LUN number, the device stayed the same this time /dev/sdc. The problem begins with the volume size, the original volume was 30GB where as the new volume is 50GB.... The information is stored somewhere and I need to be able to get rid of it somehow.

I did reboot and all volumes that no longer are available are gone. My /dev/sdc also got assigned as /dev/sda and the old /dev/sda is now assigned /dev/sdb. Volume size are correct and updated.

How do you do this without reboot?

I am using QLogic's dynamic volume scanner to refresh this information.

ql-dynamic-tgt-lun-disc.sh


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