Linux – How to extend a SAN-based Vdisk in Red Hat without rebooting

linuxstorage-area-network

First of all, I'm quite new to Linux so forgive me if I use the terms 'disks', 'partitions' and 'devices' incorrectly below!

I have a Red Hat 5.2 x86_64 server with kernel version 2.6.18-92.el5. I have several SAN-based Vdisks presented to the server, appearing as /dev/sdx and, when I create a partition, /dev/sd*x*1 . The SAN is an hp EVA-8100.

Occasionally I need to extend a disk. I can increase the size of the Vdisk via the hp Command View EVA software, but the only way currently I can get the server to recognise the additional space is to reboot the server.

For various reasons I'm not currently using an LVM. Is there a command or method I can use to get the server to recognise the additional space without rebooting the server?

Many thanks,

/Neil

Best Answer

This is what I have used for systems with dm-multipath and LVM; modify as needed:

1) Increase size of LUN in SAN
2) Check with "multipath -ll" which devices belong to said LUN
3) For each device above, do "echo 1 > /sys/block/sdX/device/rescan"
4) Go to multipath command line with "multipathd -k"
5) For each device, do "del path sdX", "add path sdX" while hoping that
the multipathing functionality works as advertised and fails over properly.
6) "resize map multipath-map-name"
7) Exit multipath command line (Ctrl-D), check with "multipath -ll" that
new size is seen.
8) pvresize, lvextend, resize2fs
9) Profit!

This works as of RHEL 5.3.

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