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USENIX Technical Program - Abstract - USENIX Annual
Conference, Freenix Session - June 2000
A 3-tier RAID Storage System with RAID1, RAID5 and compressed RAID5
for Linux
K. Gopinath, Nitin Muppalaneni, N. Suresh Kumar, Pankaj Risbood;
Indian Institute of Science, Bangalore
Abstract
This paper presents the design and implementation of a host-based driver
(a ``volume manager'') for a 3-tier RAID storage system, currently with
3 tiers: a small RAID1 tier and larger RAID5 and compressed RAID5
(cRAID5) tiers. Based on access patterns (``temperature''), the driver
automatically migrates frequently accessed data to RAID1 while demoting
not so frequently accessed data to RAID5/cRAID5. The prototype system,
called ``Temperature Sensitive Storage'' (TSS), provides reliable
persistence semantics for data migration between the tiers using ordered
updates or logging. Mechanisms are separated from policies through an
API so that any desired policy can be implemented in trusted user
processes. We also discuss the problems faced while moving from the
original implementation on the Solaris platform to Linux. Finally, we
present comparison of the performance of our design with comparable
systems using striping or RAID5.
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