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I have an existing LVM volume group of 3 disks (ext4), with 4 logical volumes. Not quite ready for the leap to a nextgen FS, I would like to balance the load on the disks. I have seen you can create VG's with striping (RAID0 equivalent), but I would like to convert the existing one. Can this be done?

marked as duplicate by Stéphane Chazelas, muru, Thomas, msp9011, roaima Jun 4 at 11:03

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  • I trust you know this already, but please be aware that a RAID0-style striping (whether actually RAID 0 or LVM) can potentially leave you without any data at all if even just one of the disks fails. You're effectively reducing your disk statistical time to failure by a considerable amount. – roaima Jun 4 at 11:03
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Don't know how far back this was documented, but in v2.02.183, man lvconvert shows:

--stripes Number
       Specifies the number of stripes in a striped LV. This is the number of PVs
       (devices) that a striped LV is spread across. Data that appears sequential in
       the LV is spread across multiple devices in units of the stripe size (see
       --stripesize). This does not apply to existing allocated space, only newly
       allocated space can be striped.

So, it won't actually convert an existing LV to a stripe. Existing data will be left as is.

0
sudo lvconvert --stripes 3 vg/lv /dev/sda1 /dev/sdb1 /dev/sdc1

Where 2 is the number of stripes, then the logical volume, then the 3 devices to stripe across. RAID 0 has no redundancy.

  • Is it really so easy? Can you show your lvdisplay -am before and after? – Totor Mar 3 '17 at 14:40
  • Doesn't work for me. lvconvert does say it can't be used like that. – Stéphane Chazelas May 28 at 9:01

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