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.
-- Daniel