Posts from — August 2005

This should not have been as difficult to do as it was. Simple concept, add disks and hence LUNs to the scan, and you want to use them on your host without having to umount all disks and reload the scsi driver.

There’s a script to rescan the scsi bus from a website that automates the process, but it didn’t work on one host I tried it.

I found that since we use qlogic drivers there’s a command that has to be run first to let the driver know that a rescan is coming (I guess).


echo "scsi-qlascan" > /proc/scsi/driver-name/adapter-id

After running it, I got this goodness in fdisk for the new device!

Disk /dev/sdd: 2000.4 GB, 2000414572544 bytes


Just so I don’t forget, here’s a link to tell you how to stop Flash popups from Firefox.

In case that link goes dead…

1. Type about:config into the Firefox location bar.
2. Right-click on the page and select New and then Integer.
3. Name it privacy.popups.disable_from_plugins
4. Set the value to 2.

The main data volume on the system at work ran out of PEs due to the old default PE size of 4 MB and 64k of PEs being in the volume group. There’s no way to change that without recreating the volume group, and blowing away everything. So I have to move the 250 gigs of crap to somewhere else, then delete the old volume group, recreate it, then move everything back. Since moving that much data requires several hours and hence downtime to users, that’s not good.

So, the idea is to move the data around live. This requires making a RAID 1 mirror on top of lvm — not usually done this way. It also requires learning enough about mdadm to be able to create a mirror without destroying the good data (ouch). The process of intially creating the mirror will require the regular lvm device be unmounted and the RAID (md) device mounted. But after that is done, the syncing of the mirror can happen live. Hence downtime is kept to an absolute minimum.

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