Plexistor SDM on AWS - User Guide

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1 Plexistor SDM on AWS - User Guide This guide was last updated for version: m1fs v1.7.0 December 2015 This AWS image is provided for free with limited support. That said, Plexistor respects your time and will be happy guide and support you, so don t hesitate to contact our support team: support@plexistor.com Table of contents: Background SDM m1fs Setup System Information & Analytics Installed packages & version information Configuration Capacity Advanced Insight Reporting a Bug Known Issues Appendix: Re mount Background Plexistor s AWS image uses the m1fs file system, which is the technological heart of Plexistor`s Software Defined Memory (SDM) architecture. m1fs use memory and FLASH as equally persistent tiers, which is perfect for either: 1. Ephemeral computing (e.g. AWS EC2) in which both memory and SSDs are inaccessible following a power failure 2. Persistent on premise computing, providing that Plexistor`s hardware compatibility list that includes NVDIMMs, is followed. Plexistor SDM software offers the fastest storage performance known. The latency of a few microseconds at the application level, while serving millions of IOPS. m1fs performance boost is valid for all files and access types: Random and sequential access Small and large files Byte and block alignment and granularity 2015 Plexistor Inc. 1

2 Write and read intensive Sync (O_SYNC) and Direct I/O (O_DIRECT) as well as async usage SDM-m1fs Setup The AWS image is already installed. By default, it uses: Ubuntu 15.10, with an upgraded kernel A single m1fs mount point A default memory split between OS and m1fs (refer to table 1) Two tiers, wherein the second SSD based tier is 12.5 times larger than the first memory based tier Ephemeral mount option Activated call home agent (CHA) for proactive support The call home agent collects various OS level logs and counters periodically. It does not collect user data stored in the file system. If other configurations are required contact support@plexistor.com. Instance type vcpu OS memory (Available for applications) Storage 1st tier Storage 2nd tier i2.xlarge GiB 16 GiB 200 GiB Carved out of 1 SSD i2.2xlarge 8 29 GiB 32 GiB 400 GiB Carved out of 2 SSDs i2.4xlarge 16 32* GiB 90 GiB 1,125 GiB Carved out of 4 SSDs i2.8xlarge 32 32* GiB 212 GiB 2,650 GiB Carved out of 8 SSDs Table 1 The main hardware resources per supported AWS instance type (*) Traditional file systems are typically the heaviest OS memory users. Plexistor`s SDM barely uses that resource (the page cache). System Information & Analytics Please use the following local command lines for system information and analysis Plexistor Inc. 2

3 Installed packages & version information To view the SDM packages & version information on your system execute: dpkg-l grep-e'(m1fs plexistor)' Configuration Command mount t m1fs lsblk /dev/pmem* Description Display mounted m1fs file systems and their mount options Display persistent memory devices and their size Capacity Command df t m1fs du sh /m1fs Description Display m1fs file systems capacity information Note that the number of used blocks includes both data and metadata blocks. Display m1fs filesystem size (counting only data blocks). Also note that the filesystem reserves the 1st tier capacity on the 2nd FLASH based tier when mounted with the t2sync flag. This is the default when using Amazon AWS. Advanced Insight Plexistor SDM provides several counters that give insight about the tiering mechanism and the system calls it serves. The counters are accessed, per mounted file system (represented by its primary mount device) with the m1fs_counters.py script: For example, if the mount directory is /m1fs, run the following to get the current counters values (with root or sudo permissions):: m1fs_counters.py/m1fs This will print three counters called T1 hits, Tier ups and Tier downs. Tiering and data locality insight can be gained by sampling two points in time, calculating the delta values and then the 1st tier miss rate according to the following formula: Δ tier ups (Δtier ups + Δt1 hits) 2015 Plexistor Inc. 3

4 Application data access insight can be gained by viewing the system call counters (as seen by the file system). This is also true for the access size (at basic granularity). To do so, run the following command (with root or sudo permissions): m1fs_counters.py-mi/m1fs This will show for example: Additional help is available via m1fs_counters.py help Reporting a Bug Please don t hesitate to contact us with any question or issue: support@plexistor.com When contacting about a bug, please attach the output file of the following script (with root or sudo permissions): /opt/m1fs-support/collect_logs.sh The output file location is /tmp/m1fs support <date>.tar.gz 2015 Plexistor Inc. 4

5 Known Issues Issue Description Bypass & Fix estimation PXS NA NA Running tail f " over a file residing on m1fs, will print the following warning: unrecognized file system type 0x d. This is a false warning and can be ignored. It will be removed in a future Linux version NA NA Upstream distribution updates might remove m1fs kernel as default boot kernel Kernel log includes the following message "d_pmem namespace0.0: unable to guarantee persistence of writes" After updating the host, please make sure that the m1fs kernel is still the default boot option. This is a false warning and can be ignored. It will be removed in a future Linux version. 543 Appendix: Re-mount The m1fs filesystem was mounted using the t2sync flag. This forward compatibility feature means that upon a proper umount system call all data and metadata will be moved to the 2nd FLASH based tier. If & when re mounting the m1fs file system, be sure to run (with root or sudo permissions): mount-tm1fs-ot2= /dev/m1fs-vg/m1fs-lv,ephemeral,t2sync/dev/pmem0m/m1fs 2015 Plexistor Inc. 5