Author Archives: maru

This release solves a bug that can lead to loss of data when btier is used with SSD’s and a recent kernel that supports discard / trim. Upgrading is highly recommended.

This release dramatically improves random read performance. This has been achieved by introducing a thread pool and implementing aio for random reads. The performance of the 0.9.9.9 release was: seq_read : io=12288MB, bw=501371KB/s, iops=125342 , runt= 25097msec rnd_read : io=2985.3MB, … Continue reading →

What’s in a name TIER has been renamed to BTIER to improve the relevance of results returned by search engines. BTIER current status The btier code is now at 0.9.9.2 and I hope to release a stable 1.0 version within … Continue reading →

Introduction This version of TIER comes with a significant number of changes. The meta data has changed to support resizing of the TIER device. Therefore this version of TIER is not compatible with previous releases. New features This version of … Continue reading →

This release of tier makes it possible to disable or enable data migration via sysfs. To disable migration: echo 1>/sys/block/tiera/tier/disable_migration To enable migration: echo 0>/sys/block/tiera/tier/disable_migration When migration is re-enabled the migration process will immediately wake up and start. This feature … Continue reading →

How TIER works Tier is a Linux kernel block device that aggregates multiple devices of different nature into one virtual block device. The idea is to combine ( expensive ) fast and ( affordable ) slow devices to build a … Continue reading →

Tier-0.2.0 adds crash recovery and some bug fixes. A brief benchmark of tier, flashcache and bcache with fio shows these results: flashcache read : io=16635MB, bw=56778KB/s, iops=14194 , runt=300017msec read : io=872528KB, bw=2908.4KB/s, iops=727 , runt=300007msec write: io=8237.5MB, bw=28117KB/s, iops=7029 … Continue reading →

This version of tier comes with some major changes. The caching layer has been removed from the code. EPRD can be used in cases where caching is needed. Also the block size has been changed so that TIER now uses … Continue reading →

Tier is a Linux kernel module that can be used to create a block device that allows automatically tiered storage. Tier can be used to aggregate up to 16 devices as one virtual device. Tier investigates access patterns to decide … Continue reading →

To get an idea of the efficiency of EPRD caching I repeated the lessfs benchmark test with EPRD caching the Intel 320 SSD. The Intel 320SSD was registered as /dev/sdc. EPRD was setup like this : ./eprd_setup -f /dev/sdc -m … Continue reading →