hsm

Using HSM

HSM stands for Hierarchical Storage Management. The concept and design are discussed in this paper: Hierarchical Storage Management - SAGE 2016.

For more information, see:

• D3.1 HSM for SAGE: Concept and Architecture Report
• D3.5 HSM for SAGE: Validation Readiness Report
• D3.9 HSM for SAGE: Final Validation Report

The m0hsm tool available in this directory allows to create composite objects in Motr, write/read to/from them and move them between the tiers (pools). Here is how to use the tool:

1. Set the following environment variables:

export CLIENT_PROFILE="<0x7000000000000001:0x480>"    # profile id
export CLIENT_HA_ADDR="172.18.1.24@o2ib:12345:34:101" # ha-agent address
export CLIENT_LADDR="172.18.1.24@o2ib:12345:41:322"   # local address
export CLIENT_PROC_FID="<0x7200000000000001:0xdf>"    # process id

Profile id of the cluster and ha-agent address on your client node can be checked with hctl status command. As well as all addresses and processes ids configured in the cluster. Consult with the cluster system administrator about which of them you can use.

2. Initialize the composite layout index:

$ m0composite "$CLIENT_LADDR" "$CLIENT_HA_ADDR" "$CLIENT_PROFILE" "$CLIENT_PROC_FID"

Note: this should be done one time only after the cluster bootstrap.

3. Configure pools ids of the tiers in ~/.hsm/config file:

M0_POOL_TIER1 = <0x6f00000000000001:0xc74> # NVME
M0_POOL_TIER2 = <0x6f00000000000001:0xc8a> # SSDs
M0_POOL_TIER3 = <0x6f00000000000001:0xca5> # HDDs

The exact ids can be taken from the output of hctl status command.

Now you are ready to use the HSM feature.

First test using m0hsm shell:

$ ./m0hsm shell

Type help for the list of available commands and their syntax:

m0hsm> help
Usage: m0hsm <action> <fid> [...]
  actions:
    create <fid> <tier>
    show <fid>
    dump <fid>
    write <fid> <offset> <len> <seed>
    write_file <fid> <path>
    read <fid> <offset> <len>
    copy <fid> <offset> <len> <src_tier> <tgt_tier> [options: mv,keep_prev,w2dest]
    move <fid> <offset> <len> <src_tier> <tgt_tier> [options: keep_prev,w2dest]
    stage <fid> <offset> <len> <tgt_tier> [options: mv,w2dest]
    archive <fid> <offset> <len> <tgt_tier> [options: mv,keep_prev,w2dest]
    release <fid> <offset> <len> <tier> [options: keep_latest]
    multi_release <fid> <offset> <len> <max_tier> [options: keep_latest]
    set_write_tier <fid> <tier>

  <fid> parameter format is [hi:]lo. (hi == 0 if not specified.)
  The numbers are read in decimal, hexadecimal (when prefixed with `0x')
  or octal (when prefixed with `0') formats.

Create an object on tier 2: create <fid> <tier_idx>

m0hsm> create 0x1000000 2
Composite object successfully created with id=0:0x1000000

Display initial state: show <fid>

m0hsm> show 0x1000000
- gen 0, tier 2, extents:  (writable)

Write data to it: write <fid> <offset> <length> <seed>

m0hsm> write 0x1000000 0x0 0x1000  42
4096 bytes successfully written at offset 0 (object id=0:0x1000000)

HSM in action: move data from tier 2 to tier 3: move <fid> <offset> <length> <src_tier> <tgt_tier> [options]

m0hsm> move 0x1000000 0 0xFFFF 2 3
Archiving extent [0-0xfff] (gen 0) from tier 2 to tier 3
4096 bytes successfully copied from subobj <0xffffff02:0x1000000> to <0xffffff03:0x1000000> at offset 0
Extent [0-0xfff] (gen 0) successfully released from tier 2

Check final state:

m0hsm> show 0x1000000
- gen 1, tier 2, extents:  (writable)
- gen 0, tier 3, extents: [0->0xfff]