Funky disk magic
Aug. 30th, 2004 05:02 pm![[personal profile]](https://www.dreamwidth.org/img/silk/identity/user.png){kind=small}
sobriqueI am here at work.
On a Bank Holiday.
And I'm doing a meta-device online expansion.
This is frightfully clever.
Basically, you take a 5 way striped mirrored system, and then add a mirrored volume to it.
Normally, this would effectively 'restructure' the disk, in such a way that the cylinders are no longer in the same layout, basically wiping your data.
The _clever_ bit here, is that I'm attaching BCV devices (EMC terminology. Stands for 'business continuance volume'. Basically just an 'extra' mirror). These BCVs will sync with the original volume, creating a track by track copy.
This copy remains available to the original host.
Then the 'original' 5x2 disk gets reassembled into a 6x2 disk structure. And then the tracks of the BCV get copied back in the same 'effective' layout as they were originally. (so striped linearly across 6 volumes rather than 5).
Which is a bit cool, because the symmetrix is hiding the fact that this is going on from the OS I'm doing it to. So I don't even have to umount the volume. Although I will have to do a growfs (diskpart extend to heretical windows users) once it's finished.
Always assuming this all works of course.
On a Bank Holiday.
And I'm doing a meta-device online expansion.
This is frightfully clever.
Basically, you take a 5 way striped mirrored system, and then add a mirrored volume to it.
Normally, this would effectively 'restructure' the disk, in such a way that the cylinders are no longer in the same layout, basically wiping your data.
The _clever_ bit here, is that I'm attaching BCV devices (EMC terminology. Stands for 'business continuance volume'. Basically just an 'extra' mirror). These BCVs will sync with the original volume, creating a track by track copy.
This copy remains available to the original host.
Then the 'original' 5x2 disk gets reassembled into a 6x2 disk structure. And then the tracks of the BCV get copied back in the same 'effective' layout as they were originally. (so striped linearly across 6 volumes rather than 5).
Which is a bit cool, because the symmetrix is hiding the fact that this is going on from the OS I'm doing it to. So I don't even have to umount the volume. Although I will have to do a growfs (diskpart extend to heretical windows users) once it's finished.
Always assuming this all works of course.
