LVM thin volume explained

Written by Gionatan Danti on . Posted in Linux & Unix

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Conclusions

Hey – where are all the dirty shell commands needed to create and manage thin volumes? Simply put, I included no command reference here. You can find some excellent documentation directly on Red Hat site [1], or lvmthin(7) man pages [2]

Commands aside, I wanted to clarify how thin volumes works. While you can argue that following the dm-devel mailing list is an ever smartly trick, I think that a condensed, graphical representation of how thin LVM works is a nice thing :)

So, when should you use thin volumes? Every time you need a dynamically managed storage pool and you can tolerate the additional fragmentation it will pose on your disk subsystem. Nearline storage system are prime candidate for it, but the perfect scenario is when you have an SSD-backed storage: flash's very low access time (compared to mechanical disks) will negate most metadata penalty, letting you really appreciate the added flexibility. Just remember to disable zeroing, as you don't want to wear that shiny SSD array, right? ;)

When should you not use thin volumes? Every time you need the absolute fastest performance (snapshot aside) and you had to deal with mechanical disks only. If this is the case, normal LVM volumes will be a better choice, as fragmentation remain #1 enemy of spinning disks.

If you want, you can email me at This email address is being protected from spambots. You need JavaScript enabled to view it.

Have a nice day!

References:

[1] - https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/6/
html/Logical_Volume_Manager_Administration/thinly_provisioned_volume_creation.html

[2] - http://man7.org/linux/man-pages/man7/lvmthin.7.html

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