Description

This article provides information about the md0 and md1 partitions.

Symptoms

This article provides information about the md0 and md1 partitions, which are displayed in the output of system storage :

root@HUB-100# run show system storage
Filesystem Size Used Avail Capacity Mounted on
/dev/da0s2a 293M 145M 125M 54% /
devfs 1.0K 1.0K 0B 100% /dev
/dev/md0 390M 390M 0B 100% /junos <
/cf 293M 145M 125M 54% /junos/cf
devfs 1.0K 1.0K 0B 100% /junos/dev/
procfs 4.0K 4.0K 0B 100% /proc
/dev/bo0s3e 24M 60K 22M 0% /config
/dev/bo0s3f 342M 49M 266M 16% /cf/var
/dev/md1 168M 18M 136M 12% /mfs <
/cf/var/jail 342M 49M 266M 16% /jail/var
/cf/var/log 342M 49M 266M 16% /jail/var/log
devfs 1.0K 1.0K 0B 100% /jail/dev
/dev/md2 39M 4.0K 36M 0% /mfs/var/run/utm  <

Solution


md0 , md1 , and so on are read-only virtual memory disks. The following commands can be used to obtain more information about these partitions:
root@HUB-100% mdconfig -l -u 0
md0 vnode 390M /cf/packages/junos
md0 is of the vnode type; so a file that is specified with it becomes the backup store for this memory disk.
root@HUB-100% mdconfig -l -u 1
md1 swap 171M
md1 is of the swap type. The storage for this type of memory disk is allocated from the buffer memory. Pages are pushed out to the swap, when the system is under memory pressure; otherwise, they stay in the operating memory.
root@HUB-100% mdconfig -l -u 2
md2 malloc 40M
md2 is of the malloc type and is for UTM. The storage for this type of memory disk is allocated with the malloc() function, which allocates uninitialized memory in the kernel address space.