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I'm working with attaching new SCSI drives to a virtual host, and the current method in my team's work instructions is to rescan the SCSI bus with:

echo "- - -" > /sys/class/scsi_host/host0/scan

However, this was written a few years back, and we've moved on to newer Linux 3.2 systems. Is the method still echo "- - -"... so many things today in Linux are a bit nicer and less arcane... is there a new method I'm unaware or is this still how its done?

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It's a virtual machine? This depends a lot on the hypervisor, and you failed to mention it. – Michael Hampton Aug 24 '13 at 5:22
I'm not sure why the hypervisor is relevant, I'm working inside the Linux VM to rescan the SCSI bus. But, for what it's worth, its VmWare. – Joe Aug 24 '13 at 5:38
Which version of VMware? VMware is a company, not a product. And which drivers are you using? – Michael Hampton Aug 24 '13 at 5:41
up vote 7 down vote accepted

In the Red Hat storage administration guide, the method you mentioned is there, along with some other options which you might prefer.

echo "- - -" > /sys/class/scsi_host/hosth/scan

[...] This procedure will add LUNs, but not remove them.

There's also the less arcane /usr/bin/, which has the advantage that it can also remove devices.

The same /sys/class/scsi_host/ tree is still there in 3.2, so there's still nothing preventing one from scanning for new devices using that method.

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Thanks Petter, good answer and good reference. – Joe Aug 24 '13 at 14:51

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