1. Nan DUN Kenjiro Taura Akinori Yonezawa The University of Tokyo Sep 12, 2007 1http://www.yl.is.s.u-tokyo.ac.jp/~dunnan/talk/070912.JSSST07.pptx

2.  Background  Related Work ◦ SSHFS ◦ FUSE  HandyFS ◦ Designs and Implementation ◦ Evaluation and Problems  Future Work Sep 12, 2007 http://www.yl.is.s.u-tokyo.ac.jp/~dunnan/talk/070912.JSSST07.pptx2

3.  User explicit sharing operation ◦ rcp, scp [OpenSSH] ◦ FTP [J. Postel, et al. 1985.], GridFTP [Globus]  Conventional Distributed File System ◦ Inner-Cluster Sharing  NFSv3, NFSv4 ◦ Inter-Cluster Sharing  AFS [OpenAFS], Gfarm [Tatebe et al. ‘04] Sep 12, 2007 3http://www.yl.is.s.u-tokyo.ac.jp/~dunnan/talk/070912.JSSST07.pptx

4.  Complexity of conventional DFSs ◦ Client-Server Configurations ◦ Administrative Privilege ◦ Typical Firewall Setting of the Grid  Simplicity of SSHFS [http://fuse.sourceforge.net/sshfs.html] ◦ Only need available SSH connection ◦ Client-side mount only ◦ User-level Operations without privileges Sep 12, 2007 http://www.yl.is.s.u-tokyo.ac.jp/~dunnan/talk/070912.JSSST07.pptx4

5.  Create local mount point ◦ user@hongo000:~$ mkdir mnt_chiba  Mount remote directory to mount point ◦ user@hongo000:~$ sshfs chiba000.intrigger.nii.ac.jp:/sharedir mnt_chiba  Access remote files via local mount point ◦ user@hongo000:~$ [ls, rm, cp, mkdir] mnt_chiba Sep 12, 2007 http://www.yl.is.s.u-tokyo.ac.jp/~dunnan/talk/070912.JSSST07.pptx5

6. Sep 12, 2007 http://www.yl.is.s.u-tokyo.ac.jp/~dunnan/talk/070912.JSSST07.pptx6 fuse hostA_mountpointhostB_mountpoint SSH client hostA SSHFS User Application General File System Call SSH Commands Translation fuse SSH client hostB

7. Sep 12, 2007 http://www.yl.is.s.u-tokyo.ac.jp/~dunnan/talk/070912.JSSST07.pptx7 Data Transfer Rate (Mbps) SSHFS-FUSE overhead

8.  Disadvantages of Merely Using SSHFS ◦ Non-scalable  Users have to create many mount points for hosts ◦ Non-unified namespace  Files under different mount points (hosts) should be manipulated separately  Motivation of HandyFS ◦ Inherit simplicity from SSHFS ◦ Create a scalable mount for many hosts ◦ Ad-hoc create a unified namespace for files on many hosts Sep 12, 2007 http://www.yl.is.s.u-tokyo.ac.jp/~dunnan/talk/070912.JSSST07.pptx8

9. Sep 12, 2007 http://www.yl.is.s.u-tokyo.ac.jp/~dunnan/talk/070912.JSSST07.pptx9  Create ONE local mount point ◦ user@hongo000:~$ mkdir mnt_all  Mount MULTIPLE remote directories to mount point ◦ user@hongo000:~$ handyfs chiba000.intrigger.nii.ac.jp:/sharedir1 chiba001.intrigger.nii.ac.jp:/sharedir2...... mnt_all  Access remote files via local mount point ◦ user@hongo000:~$ [ls, rm, cp] mnt_all

10. Sep 12, 2007 http://www.yl.is.s.u-tokyo.ac.jp/~dunnan/talk/070912.JSSST07.pptx10 FUSE Kernel Module User Application HandyFS SSHFS Host1 Host2 User Kernel SSHFS The trick is using FUSE twice 1. SSHFS mount for remote host 2. Local mount for directory merge /handyfs_mnt/sshfs_mnt1

11. Source directory Tree at HostB Source directory Tree at HostA  Directories Merge ◦ Source directories and Target (virtual) directory  Source directory: SSHFS mount points for each host  Target directory: Directory in HandyFS namespace Sep 12, 2007 http://www.yl.is.s.u-tokyo.ac.jp/~dunnan/talk/070912.JSSST07.pptx11 /mnt_hostA /A /B /B/C /mnt_hostB /B /C /B/D / / /A /B /B/C Virtual directory Tree /C /B/D

12.  Directories Merge ◦ Source directories and Target (virtual) directory ◦ Directory Table  To remember virtual directory is merged from which source directory ◦ On-Demand Merge Operation  Merge operation occurs only when request reach non- merged path Sep 12, 2007 http://www.yl.is.s.u-tokyo.ac.jp/~dunnan/talk/070912.JSSST07.pptx12 /cmndir /srcdirA/cmndir Virtual DirectorySource Directories /srcdirB/cmndir Implemented by using BerkeleyDB to achieve good performance

13.  File Lookup Sep 12, 2007 http://www.yl.is.s.u-tokyo.ac.jp/~dunnan/talk/070912.JSSST07.pptx13 Lookup a file with full pathname Retrieve source directory entries from directory table Lookup file in each retrieved source directory entries If target pathname has not been merged, then merge and store into directory table Return result to user On-demand Merge

14.  Directory Split ◦ Remove one or several source directories from virtual directory, we have two alternatives  Remove directory table entries  Heavy Operation: Search entire directory table  Re-insert overhead if source become available again  Blind user view of source directories by filtering  Use a in-memory filter to mark current available sources  File lookup results are filtered before returning to user  Efficient and re-usable Sep 12, 2007 http://www.yl.is.s.u-tokyo.ac.jp/~dunnan/talk/070912.JSSST07.pptx14

15.  Directory Split Sep 12, 2007 http://www.yl.is.s.u-tokyo.ac.jp/~dunnan/talk/070912.JSSST07.pptx15 Lookup a file with full pathname Retrieve source directory entries from directory table Lookup file in each retrieved source directory entries If target pathname has not been merged, then merge and store into directory table Return result to user Filtering out results that are from removed source directories

16.  File Creation ◦ File is created at random source directory ◦ For directory file, an entry is created in directory table  Directory Read ◦ Similar as file lookup  Lookup target directory  Read all entries from source directories that composed of target directory Sep 12, 2007 http://www.yl.is.s.u-tokyo.ac.jp/~dunnan/talk/070912.JSSST07.pptx16

17.  Some Practical Problems ◦ Same file from multiple sources  Not compatible with UNIX file semantics  Define priority of source directory  Only files from source directory with high priority are visible to user ◦ Stale of Directory Table  Remote directory tree may be modified by its local operations  Periodically update Sep 12, 2007 http://www.yl.is.s.u-tokyo.ac.jp/~dunnan/talk/070912.JSSST07.pptx17

18.  Experimental Environments ◦ InTrigger Platform: https://www.logos.ic.i.u- tokyo.ac.jp/intrigger/https://www.logos.ic.i.u- tokyo.ac.jp/intrigger/ Sep 12, 2007 http://www.yl.is.s.u-tokyo.ac.jp/~dunnan/talk/070912.JSSST07.pptx18 Hardware/SoftwareSpecification CPUCore2 Duo 2.13Hz Memory4GB NetworkGigabit Ethernet OSLinux 2.6.18 FUSE Kernel Interface7.8 FUSE Library2.7.0 SSHFS1.8

19.  Experimental Results ◦ Data Transfer Rate Sep 12, 2007 http://www.yl.is.s.u-tokyo.ac.jp/~dunnan/talk/070912.JSSST07.pptx19 SSHFS-FUSE overhead TWICE-FUSE- MOUNT overhead

20.  Experimental Results ◦ Source Compilation Sep 12, 2007 http://www.yl.is.s.u-tokyo.ac.jp/~dunnan/talk/070912.JSSST07.pptx20 Wide-Area Latency SSHFS Overhead Wide-Area Latency SSHFS Overhead TWICE-FUSE- MOUNT overhead

21.  Performance ◦ HandyFS itself  To remove MOUNT-TWICE overhead ◦ SSHFS performance  Need be tuned at source level  Scalability ◦ “One-to-All” mount  “All-to-All” mount Sep 12, 2007 http://www.yl.is.s.u-tokyo.ac.jp/~dunnan/talk/070912.JSSST07.pptx21