Abstract
While Copy-On-Write (COW) snapshot is the popular technique for online data protection, its first write request suffers from severe performance penalty because 3 I/Os are needed for each data block after creating snapshot. This paper proposes Pipelining-based COW (PCOW) method to minimize the snapshot impact on the first write request. When origin data is read from origin volume to a buffer queue, pending host write request can be serviced immediately. Origin data will be deferred to write to the snapshot volume in a background asynchronous thread. In order to demonstrate PCOW feasibility and efficiency, we have implemented both COW and PCOW in a standard iSCSI target as independent modules. We use popular benchmarks to quantitatively compare PCOW and COW techniques. Numerical results show that PCOW can effectively decrease first write penalty and improve performance.
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References
Azagury, A., Factor, M.E., Satran, J., Micka, W.: Point-in-time copy: Yesterday, today and tomorrow. In: Proceedings of the 10th NASA Goddard, 19th IEEE Conference on Mass Storage Systems and Technologies (2002)
Duzy, G.: Match snaps to apps, Storage, Special Issue on Managing the information that drives the enterprise, pp. 46–52 (2005)
EMC Corp.: EMC TimeFinder Family, http://www.emc.com/products/software/timefinder.jsp
Sankaran, A., Guinn, K., Nguyen, D.: Volume Shadow Copy Service (2004), http://www.microsoft.com
Hitachi Ltd.: Hitachi ShadowImage implementation service (2001), http://www.hds.com/copy_on_write_snapshot_467_02.pdf
Santry, D.S., Feeley, M.J., Hutchinson, N.C., Veitch, A.C., Carton, R.W., Ofir, J.: Deciding when to forget in the Elephant file system. In: Proceedings of 17th ACM Symposium on Operating System Principles, Charleston, SC, pp. 110–123 (1999)
Soules, C.A.N., Goodson, G.R., Strunk, J.D., Ganger, G.R.: Metadata efficieny in versioning file systems. In: Proceedings of the 2nd USENIX Conference on File and Storage Technologies, San Francisco, CA, pp. 43–58 (2003)
Xiao, W., Liu, Y., Yang, Q., Ren, J., Xie, C.: Implementation and Performance Evaluation of Two Snapshot Methods on iSCSI Target Storages. In: Proceedings of NASA/IEEE Conference on Mass Storage Systems and Technologies, College Park, Maryland (2006)
Mauelshagen, H.: Logical Volume Manager (LVM2) (2004)
UNH-iSCSI Initiator and Target for Linux, http://unh-iscsi.sourceforge.net
Katcher, J.: PostMark: a new file system benchmark. Technical report TR3022. Network Appliance (1997)
IoMeter benchmark (version 2006.07.27), http://sourceforge.net/projects/Iometer/
Warfield, A., Ross, R., Fraser, K., Limpach, C., Steven, H.: Parallax: Managing Storage for a Million Machines. In: Proceedings of the 10th USENIX Workshop on Hot Topics in Operating Systems, Santa Fe, NM, pp. 1–11 (2005)
Bloom, B.: Space/time trade-offs in hashing coding with allowable errors. Communication of the ACM 13(7), 422–426 (1970)
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Wang, Z., Feng, D., Zhou, K., Wang, F. (2008). PCOW: Pipelining-Based COW Snapshot Method to Decrease First Write Penalty. In: Wu, S., Yang, L.T., Xu, T.L. (eds) Advances in Grid and Pervasive Computing. GPC 2008. Lecture Notes in Computer Science, vol 5036. Springer, Berlin, Heidelberg. https://doi.org/10.1007/978-3-540-68083-3_27
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DOI: https://doi.org/10.1007/978-3-540-68083-3_27
Publisher Name: Springer, Berlin, Heidelberg
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