EXT4/LVM recommendations for 3TB of mdbox ?

dmiller at amfes.com dmiller at amfes.com
Wed Jun 24 20:35:46 UTC 2015

On 2015-06-24 13:03, Nicolas C. wrote:
> Hello,
> Do you have recommendations on EXT4 and LVM options for a 3TB
> file-system for mdbox?
> We currently use the mbox format on a XFS with poor performances since
> the update in v2.1 (Debian).

What qualifies as "poor performance"?  How many users?

> We will switch to EXT4 to have the possibility of shrinking the
> file-system if needed (which is not possible with XFS), we currently
> have LVM partitions but with mdbox we will use LVM snapshots to backup
> the server in a consistent state.
> So,
>  - any particular options to use with mkfs.ext4 for the creation of the 
> FS ?
It's not what you asked - but the options for XFS creation and mounting 
can make a fair bit of difference.

>  - do you recommend a «thin» logical volume ? Our storage (IBM
> Storwize v7000) already have thin provisioning capabilities.
> The server will be a VMware virtual machine running Debian with RDM
> LUNs of 500GB. Data blocks will be automatically spread across several
> RAID disk (SSD, SAS, SATA) by the v7000. The «mdbox_rotate_size» will
> be configured around 10MB.
I happen to be using 32MB.

Just going to mdbox can make a measurable performance increase.  I also 
make use of single-instance-storage.

Everyone is going to have their own opinions and experiences with 
filesystems.  I personally have had mixed issues with EXT3/4 but have 
enjoyed great success with XFS.  Admittedly my server is probably much 
smaller than others but I still need to depend on it.


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