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Our application uses EBS to store data. The storage requirement of the application grows rapidly as users signup. We need to do it online so that users don't experience downtime with the application. So, here is what we do:

  • The file system is XFS.
  • We are using LVM and RAID0.
  • Whenever we fill up 40% of total storage, we add two EBS volumes, create a RAID0 array out of them. Then we add this array to the LVM to extend the file system.

This way, the application can continue to read and write to the file system, while the underlying file system grows.

Yesterday, we experienced corruption in some of the database files that were being written into.

My question is:

  • is it safe to use RAID0 with LVM and XFS?
  • is it safe to use xfs_grow to increase storage while the files in the file system are being written into?
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Sabya
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    What do you mean you "mount it to the same directory"? Do you umount the previous volume's file system first or are you depending on open files there to remain on the previous (now hidden) file system? What kind of files are you putting on the EBS volume(s)? database? – Eric Hammond Jan 27 '12 at 12:48

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is it safe to use RAID0 with LVM and XFS?

In general, yes.

is it safe to use xfs_grow to increase storage while the files in the file system are being written into?

Yes, this is how it is intended to be used.

That said, I have posted questions in the comments above about the specifics of what you are trying to do as it sounds a bit strange.

Eric Hammond
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  • Sorry for using a wrong term. I just edited the question. – Sabya Jan 27 '12 at 13:15
  • In theory, I don't see anything obviously incorrect about the approach you describe, extending with LVM, but database corruption implies that something went wrong. It does seem to me that it may be difficult to get consistent snapshots across all volumes and to put together the volumes or snapshots with LVM/RAID after a major failure. – Eric Hammond Jan 27 '12 at 22:20
  • LVM is generally a bad idea in Xen? According to this reply: http://www.spinics.net/lists/xfs/msg09353.html. Now I am more confused. – Sabya Jan 31 '12 at 08:40