→ Applies to: Hyperion 9.x and above

This article describes how to create a dedicated mirrored ZFS Separate Intent Log (SLOG) using free space available on the operating system disks. Two 10 GB partitions are created on the mirrored boot disks and added as a mirrored log device to an existing ZFS pool.

IMPORTANT
This procedure modifies the partition table of the operating system disks. Ensure that sufficient unallocated space exists before proceeding. Verify that the new partitions are not in use by any filesystem or RAID device.

Step 1. Connect to Hyperion appliance via SSH as admin

ssh admin@<your_ip_address_or_hostname>

Step 2. Become Super User

sudo su

Identify the Operating System Disks

Find the new Drive

lsblk -o NAME,SIZE,MOUNTPOINT,TYPE,VENDOR,MODEL,SERIAL

EXAMPLE OUTPUT

NAME      SIZE TYPE MOUNTPOINTS
sda     447.1G disk
├─sda1   512M part /boot/efi
├─sda2     2G part
│ └─md126
└─sda3 195.3G part
  └─md127 /
sdb       7.3T disk
sdc       7.3T disk
sdd     447.1G disk
├─sdd1     2G part
│ └─md126
└─sdd2 195.3G part
  └─md127 /

In this example:

• sda and sdd are the mirrored operating system disks.
• sdb and sdc are data disks.

The remainder of this article assumes the operating system disks are /dev/sda and /dev/sdd.

Verify Available Free Space

Display the current partition layout and available free space (replace <disk> with the correct name of the disk from Step 3)

parted /dev/<disk> unit GiB print free
parted /dev/<disk> unit GiB print free

Identify the free region at the end of each disk before proceeding

Create a 10 GB Partition

Step 1. Create a new partition within the available free space (replace <disk> with the correct name of the disk from Step 3)

parted -s /dev/sda mkpart primary <start>GiB <start+10>GiB
parted -s /dev/sdd mkpart primary <start>GiB <start+10>GiB

Replace <start> with the beginning of the free space reported by parted in the previous step.

Step 2. Reload the partition table

partprobe

udevadm settle

Step 3. Verify the new partitions

lsblk

Identify the Persistent Device Names

List the persistent device identifiers

ls -l /dev/disk/by-id/

EXAMPLE OUTPUT

/dev/disk/by-id/scsi-3500a0751547a7af4-part4
/dev/disk/by-id/scsi-3500a0751547a7aee-part3

Using /dev/disk/by-id/ paths is strongly recommended instead of /dev/sdX, as they remain stable across reboots and hardware enumeration changes

Verify the Partitions Are Unused

Check if the Partitions are Unused (replace <scsi_disk> with the correct scsi disk name from Identify the Persistent Device Names subsection)

lsblk -f \
  /dev/disk/by-id/<scsi_disk> \
  /dev/disk/by-id/<scsi_disk>

EXAMPLE OUTPUT

lsblk -f \
  /dev/disk/by-id/scsi-3500a0751547a7af4-part4 \
  /dev/disk/by-id/scsi-3500a0751547a7af4-part4

Add the SLOG 

If you're on two disks to create a mirrored SLOG:

zpool add -f <pool_name> log mirror \
    /dev/disk/by-id/<scsi_disk> \
    /dev/disk/by-id/<scsi_disk>

Replace <scsi_disk> with the correct scsi disk name from Identify the Persistent Device Names subsection

EXAMPLE OUTPUT

zpool add -f <hybrid log mirror \
    /dev/disk/by-id/scsi-3500a0751547a7af4-part4 \
    /dev/disk/by-id/scsi-3500a0751547a7aee-part3

If you're on single disk without mirror:

zpool add -f <pool_name> log \
    /dev/disk/by-id/<scsi_disk>

Replace <scsi_disk> with the correct scsi disk name from Identify the Persistent Device Names subsection

EXAMPLE OUTPUT

zpool add -f <hybrid log \
    /dev/disk/by-id/scsi-3500a0751547a7af4-part4

Verify the Configuration

Step 1. Check the pool status

zpool status hybrid

EXAMPLE OUTPUT

logs
 mirror-1
   scsi-3500a0751547a7af4-part4
   scsi-3500a0751547a7aee-part3

Ensure the log devices appear under the logs section as a mirror.

Step 2. Monitor SLOG activity

zpool iostat -v hybrid 1

The log devices should appear under the logs section with active I/O statistics.