When using FMADIO Packet capture system for analytics processing SSD resources can be split into Capture devices and Scratch disk space. In scratch disk space 1-16TB of SSD can be mounted as a general purpose file system used to store temporarily/intermediate network packet processing results.
The system should have scratch disks setup and visible on the GUI as follows, if this has not been configured contact support@fmad.io on how to configure
In the above example there are 2 disks SCR0 and SCR1 enabled for scratch disk these are seen on the file system as
fmadio@fmadio20v3-287:~$ ls -al /opt/fmadio/disk/scr*
lrwxrwxrwx 1 root root 12 Jun 6 17:02 /opt/fmadio/disk/scr0 -> /dev/nvme2n1
lrwxrwxrwx 1 root root 12 Jun 6 17:02 /opt/fmadio/disk/scr1 -> /dev/nvme0n1
fmadio@fmadio20v3-287:~$
NOTE: the /dev/* mount point may change from time to time, please use the /opt/fmadio/disk/scr* path name for all operations.
Creating RAID0 partition
Start by creating a /dev/md1 RAID0 partition as follows
This creates a /dev/md1 partition as shown with lsblk command. Can see the /dev/md1 device
fmadio@fmadio20v3-287:~$ lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
sdd 8:48 0 3.7T 0 disk
sdb 8:16 0 3.7T 0 disk
nvme2n1 259:0 0 447.1G 0 disk
`-md1 9:1 0 894G 0 raid0
nvme1n1 259:3 0 477G 0 disk
sde 8:64 0 3.7T 0 disk
sdc 8:32 0 3.7T 0 disk
sda 8:0 0 238.5G 0 disk
|-sda2 8:2 0 223.6G 0 part /mnt/store0
`-sda1 8:1 0 14.9G 0 part /mnt/sda1
nvme0n1 259:1 0 447.1G 0 disk
`-md1 9:1 0 894G 0 raid0
nvme3n1 259:2 0 477G 0 disk
fmadio@fmadio20v3-287:~$
More detail via the mdadm --detail command
fmadio@fmadio20v3-287:~$ sudo mdadm --detail /dev/md1
/dev/md1:
Version : 1.2
Creation Time : Sun Jun 6 17:43:12 2021
Raid Level : raid0
Array Size : 937440256 (894.01 GiB 959.94 GB)
Raid Devices : 2
Total Devices : 2
Persistence : Superblock is persistent
Update Time : Sun Jun 6 17:43:12 2021
State : clean
Active Devices : 2
Working Devices : 2
Failed Devices : 0
Spare Devices : 0
Chunk Size : 512K
Name : fmadio20v3-287:1 (local to host fmadio20v3-287)
UUID : 06234ac8:694ae295:3659e4fc:b59a7d55
Events : 0
Number Major Minor RaidDevice State
0 259 0 0 active sync /dev/nvme2n1
1 259 1 1 active sync /dev/nvme0n1
fmadio@fmadio20v3-287:~$
Create BTRFS Filesystem
The block device /dev/md1 is block level only, it contains no mountable file system. Next create btrfs filesystem on the device as follows
fmadio@fmadio20v3-287:~$ sudo mkfs.btrfs /dev/md1
btrfs-progs v5.12.1
See http://btrfs.wiki.kernel.org for more information.
Detected a SSD, turning off metadata duplication. Mkfs with -m dup if you want to force metadata duplication.
Performing full device TRIM /dev/md1 (894.01GiB) ...
Label: (null)
UUID: 5432ceac-b3d1-4b1c-8b69-d622542a9184
Node size: 16384
Sector size: 4096
Filesystem size: 894.01GiB
Block group profiles:
Data: single 8.00MiB
Metadata: single 8.00MiB
System: single 4.00MiB
SSD detected: yes
Zoned device: no
Incompat features: extref, skinny-metadata
Runtime features:
Checksum: crc32c
Number of devices: 1
Devices:
ID SIZE PATH
1 894.01GiB /dev/md1
fmadio@fmadio20v3-287:~$
Mount the BTRFS Filesystem
By default FMADIO Packet Capture systems at boot time mount BTRFS with lzo disk compression. Compression can be enabled or disabled with BTRFS on-the-fly. In this case we will mount it the same as capture system does at boot time.
fmadio@fmadio20v3-287:~$ sudo mount -t btrfs -o compress=lzo /dev/md1 /mnt/store1
fmadio@fmadio20v3-287:~$
Then check the mount point with lsblk. Below we can see /dev/md1 is mounted on /mnt/store1
fmadio@fmadio20v3-287:~$ lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
sdd 8:48 0 3.7T 0 disk
sdb 8:16 0 3.7T 0 disk
nvme2n1 259:0 0 447.1G 0 disk
`-md1 9:1 0 894G 0 raid0 /mnt/store1
nvme1n1 259:3 0 477G 0 disk
sde 8:64 0 3.7T 0 disk
sdc 8:32 0 3.7T 0 disk
sda 8:0 0 238.5G 0 disk
|-sda2 8:2 0 223.6G 0 part /mnt/store0
`-sda1 8:1 0 14.9G 0 part /mnt/sda1
nvme0n1 259:1 0 447.1G 0 disk
`-md1 9:1 0 894G 0 raid0 /mnt/store1
nvme3n1 259:2 0 477G 0 disk
fmadio@fmadio20v3-287:~$
Check BTRFS compression level
Checking the compression level with BTRFS requires calculating the raw storage and the compressed storage.
fmadio@fmadio20v3-287:/mnt/store1$ du -h -d 1
3.0G ./cache
3.0G .
fmadio@fmadio20v3-287:/mnt/store1$
fmadio@fmadio20v3-287:/mnt/store1$ sudo btrfs fi show
Label: none uuid: 5432ceac-b3d1-4b1c-8b69-d622542a9184
Total devices 1 FS bytes used 751.07MiB
devid 1 size 894.01GiB used 2.02GiB path /dev/md1
fmadio@fmadio20v3-287:/mnt/store1$
In the above example we see /mnt/store1 has 3.0 GB worth of data (using du)
In the above example we see /mnt/store1 has used 751.MiB of actual storage capacity (using btrfs fi show)
Based on the above math (3112MB / 751MB) , the compression rate is ~ x4.04
