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Posts in Storage
Problems growing RAID6 MD devices on RHEL5 systems
I attempted to grow an existing RAID6 MD device this week, and ran into the following error when I performed the grow operation: It appears the ability to grow a RAID6 device was added in the Linux 2.6.21 ker nel, and this feature has yet to be backported to RHEL5 (the mdadm manual page implies that this should work, so I reckon there is a documentation mismatch). If you are enountering this error, you will need to switch to a newer kernel in order to be able to grow RAID6 devices on RHEL5 systems. 2.6.33 worked like a champ, and I hope this issue is addressed when RHEL6 ships.
$ read more →VTL project for Linux
I came across the Linux tape library project website the other night, and this looks like a sweet project. If we could combine this solution with ZFS, the combination would be truly incredible! I need to install the LVTL software in my lab and give it a spin!
$ read more →Configuring and monitoring the T5220 hardware RAID controller
The Sun T5220 comes with a built-in RAID controller, which supports all of the standard RAID levels (0 - 6). Configuring one or more devices to participate in a RAID Configuration is dead simple, since you can use the Solaris raidctl utility. The last T5220 I configured had a root file system that was going to reside on the built-in RAID controller, so I had to boot into single user mode to create my volume. To create a RAID1 volume using the devices c1t0d0 and c1t1d0 (you can get the devices via format or raidctl), you can run raidctl with the "-c" (create raid volume) option, and the names of the disks to mirror: I also wanted to be able to use the cache on the RAID controller, which can be enabled using the raidctl "-p" (set property) option: Once I had a working RAID1 volume, I created a label on the device with fdisk and proceeded to perform a Solaris 10 installation…
$ read more →Using the Linux parted utility to re-create a lost partition table
I ran into an issue last week where two nodes using shared storage lost the partition table on one of the storage devices they were accessing. This was extremely evident in the output from fdisk: Fortunately the system in question still had the /proc/partition data in tact, so I stashed that in a safe location and came up with a plan to re-recreate the partition tables using this data. Given the following /proc/partitions data for the device listed above: I can see that the device had two partion table entries, and the device was approximately 100GB in size. To re-create the partition tables, I used the parted mkpart command passing it the starting and ending sector numbers I wanted written to the partition table: Now you may be asking yourself where did I get the starting and ending sectors from…
$ read more →Backing up your COMSTAR storage configuration
I have been playing around with the COMSTAR iSCSI and FC port providers for the past few months, and other than a number of problems with the emlxs driver, they appear to work pretty well. As I've been experimenting, I wanted to back up my configuration in case something happened to my server. COMSTAR uses SMF and the underlying block device to store configuration data, so you can use svccfg to backup the configuration: If you ever need to restore the configuration, you can attach the storage and run an import: COMSTAR has some serious potential, and I'm looking forward to seeing the project grow in 2010!
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