online hierarchical storage manager for linux ottawa linux symposium 2009
TRANSCRIPT
Who am I ?
Greg Freemyer CTO and Litigation Triage Solutions Specialist at
The Norcross Group Using UNIX since 1983, and have an interest in
storage systems HP certified Master SAN Architect Participate in several kernel mailing lists and try
to help out on kernelnewbies I did not write any of OHSM, but I became an
advisor to the project after becoming aware of them via the kernelnewbies mailing list
OHSM Team
The ohsm team was formed to compete in various university competitions University of Pune, India
The team comprises of currently six members Project Mentor- Sandeep Kumar Sinha, NetApp, India Students - Rishi Bhushan Agrawal, Rohit Kumar Sharma, Rohit Vashist, Sneha
Hendre, Vineet Agarwal Competition results
Third Prize at Cognizance’ 09 held at Indian Institute of Technology, Roorkee. Consolation prize at Techkriti’ 09 held at Indian Institute of Technology,
Kanpur. First Prize at INNOVATION 2k9 held at Cummins College of Engineering, Pune. Second Prize at Jishin’ 09 held at Bharti Vidyapeeth College of Engineering for
Women, Pune. Third Prize at Techno Dream’ 09 held at Maharashtra Academy of
Engineering, Alandi.
Why OHSM ?
Extremely large cost ratio between low-cost consumer grade storage to high-end SSD class storage Bare SATA ~ $100/TB Bare Intel SSD ~
$5,000/TB* Enterprises need online relocation of data
between storage tiers Enterprise Application Security Audits make
moving data from one logical location to another difficult and expensive
No open source solution
* Based on $750 for a 160GB Intel SSD on July 9, 2009
File System Scanner
TRIGGERRelocation Policy
Dest = 3
Home= 1
Tier 1
Tier 2
Tier 3
Home = 3Dest = 0Dest = 0
OHSM Goals ?
Leveraging Hybrid aggregates (volumes) Policy based initial placement of files Online relocation of data between tiers Leverage user space, existing ABIs, and
existing kernel functionality Minimal Patches to existing filesystem(s) Kernel Module isolating OHSM kernel logic Mainline kernel inclusion
Complexity and Challenges
Relocating open files Keeping file system online Ranged block allocation Getting device mapping from device
mapper
Status of project
Prototype implementation on ext2 with both kernel and user space code
Design documents and full source available for ext2 prototype available for download
ext3 testing in progress ext4 is in the architectural discussion
stage
User Space Components
XMLParser
Device Mapper Library
OHSMAdministrat
or
Device Topology
OHSMUser
Interface
Sample policy file in XML
<DEVICES>
<DEV_TIER_INFO>
<NR_TIERS>3</NR_TIERS>
<NR_DEVICES>6</NR_DEVICES>
</DEV_TIER_INFO>
<DEV_TIER>
<TIER>1</TIER>
<DEVICE>/dev/md4</DEVICE>
<DEVICE>/dev/md5</DEVICE>
<TIER>2</TIER>
<DEVICE>/dev/md3</DEVICE>
<TIER>3</TIER>
<DEVICE>/dev/md1</DEVICE>
<DEVICE>/dev/md2</DEVICE>
<DEVICE>/dev/md6</DEVICE>
</DEV_TIER>
</DEVICES>
Configuration Files
/etc/ohsm/dtd_alloc.dtd /etc/ohsm/dtd_reloc.dtd /etc/ohsm/dtd_device.dtd /etc/ohsm/ohsm.conf
User space / Kernel APIs
Enable/Disable OHSM ioctl services Set Allocation and Relocation Policies Set Tier Device Mappings Enable/Disable Relocation Policy ( Based
on Relocation rule ID or Rule No) Triggering relocation Get Tier Status (No. of allocated/free
blocks)
Ext4 implementation
New Architecture design for ext4 supporting per-inode preallocation and per-CPU locality preallocation
Ted Tso's Dec. 8, 2008 ext4 post 1 - 3 new ioctls: Blocks NOT to allocate from – global Preferred Block range to Allocate from - Inode
specific replace blocks with donor blocks - Inode
specific
1 - http://markmail.org/message/qp7zjhhdzxum7rfn
Ext4 Implementation….
Akira Fujita Patches EXT4_IOC_ADD_GLOBAL_ALLOC_RULE 2 – rfc EXT4_IOC_ADD_INODE_ALLOC_RULE 2 – rfc EXT4_IOC_MOVE_EXT 3 - in 2.6.31-rc series
Open/Create Hooks Home and Destination Tier, where to store?
2 - http://markmail.org/message/yigzopzx2gkdjyw3
3 - http://markmail.org/message/a43cgtefhhz45slc
What is the OHSM Project ?
Effort to build platform for HSM on Linux Idea came when thinking of hybrid
aggregates (SSD + Rotational) Its hosted at code.google.com/p/fscops
and ohsm.sourceforge.net Open to all
Future of OHSM ?
A free Open Source Hierarchical Storage Manager for Linux framework
Ext4 support Submission of patches to mainline Allocation based on directories Analytical Engine to trigger relocation Support for extending FS when Logical
Volume is extended Allocating inodes from optimum tier based on
policy