LVM Memory Usage

Linux and Unix-Like Red Hat
1

Hello
I am using LVM to create volumes.

After creating the volumes using "lvcreate" and then formating them as "ext3".
I mounted these volumes to find around 40 -50GB space wasted.

Any suggestions why?

 # df -h
Filesystem            Size  Used Avail Use% Mounted on
/dev/sdb1             111G   16G   90G  15% /
/dev/sda1              99M   24M   71M  25% /boot
tmpfs                 5.9G     0  5.9G   0% /dev/shm
/dev/mapper/vg_oracle-lv_u91
                      699G  197M  664G   1% /u91
/dev/mapper/vg_oracle-lv_u92
                      955G  200M  907G   1% /u92
2

Every one of the "real" disk devices shows the same thing. Short answer is that the filesystem uses disk space on the disk that is not reported as used by the file system.
This is normal behavior. As time goes on the difference will become a smaller percentage - the space is not "wasted".

1 Like
3

I guess I needed refresher for my Disk Partitions basics.
Forgot that about 5% is used for root access on all partitions and this looks like it.

Was able to reduce this using tune2fs command.

4

Also, the file systems leave a small bit of space "unavailable" on purpose. This allows for the root user to access and perform functions in a file system that shows 100% full and not have a full disk make the system totally unusable. You don't want to remove that.

1 Like
5

I would suggest rather than decreasing the reserved block percentage, use tune2fs -u to specify a user id (usually user id of the application which will use the file system, I'm assuming it's oracle in this case) which will use the reserved blocks.

In this way, you will be ensuring free space for the application, even when other users will not have any space left on that filesystem to write to.

1 Like
6

Hello Sixsprings... I reducerd the percentage to 3% and have 8GB space still allocated for root access. Did not reduce the size to 0. THink this should be enough.

---------- Post updated at 02:15 AM ---------- Previous update was at 02:14 AM ----------

Thank you for the suggestion will keep in mind this option for future use...