Baoverlay: a block-accessible overlay file system for fast and efficient container storage
Baoverlay: a block-accessible overlay file system for fast and efficient container storage
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DOI：
10.1145/3419111.3421291
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发表时间：
2020-10
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通讯作者：
Yu Sun;Jiaxin Lei;Seunghee Shin;Hui Lu
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作者：
Yu Sun;Jiaxin Lei;Seunghee Shin;Hui Lu
容器存储通常依赖于覆盖文件系统来在备份文件系统上覆盖只读容器映像。虽然覆盖文件系统方法对大多数现有的备份文件系统是透明的，并且与大多数现有的备份文件系统兼容，但它会给容器化应用程序带来不小的I/O开销，特别是对于写入：要写入源自只读容器映像的文件，整个文件将被复制到单独的可写存储层，导致长的写入延迟和容器存储的低效使用。在本文中，我们提出了BAOverlay，一个轻量级的，块可访问的覆盖文件系统：配备了一个新的块可访问性属性，BAOverlay不仅利用了使用异步写时复制机制快速文件更新的好处，而且还启用了一种新的文件格式，以有效地利用容器存储空间。我们已经在Linux Ext4上开发了一个BAOverlay的原型。我们对微基准测试和实际应用程序的评估表明了BAOverlay的有效性，提高了写入性能和按需容器存储使用率。
Container storage commonly relies on overlay file systems to interpose read-only container images upon backing file systems. While being transparent to and compatible with most existing backing file systems, the overlay file-system approach imposes nontrivial I/O overhead to containerized applications, especially for writes: To write a file originating from a read-only container image, the whole file will be copied to a separate, writable storage layer, resulting in long write latency and inefficient use of container storage. In this paper, we present BAOverlay, a lightweight, block-accessible overlay file system: Equipped with a new block-accessibility attribute, BAOverlay not only exploits the benefit of using an asynchronous copy-on-write mechanism for fast file updates but also enables a new file format for efficient use of container storage space. We have developed a prototype of BAOverlay upon Linux Ext4. Our evaluation with both micro-benchmarks and real-world applications demonstrates the effectiveness of BAOverlay with improved write performance and on-demand container storage usage.