Intel Cache Acceleration Software (Intel CAS) for Linux* v2.9 (GA) Release Notes June 2015 Revision 010 Document Number: 328497-010
Notice: This document contains information on products in the design phase of development. The information here is subject to change without notice. Do not finalize a design with this information. INFORMATION IN THIS DOCUMENT IS PROVIDED IN CONNECTION WITH INTEL PRODUCTS. NO LICENSE, EXPRESS OR IMPLIED, BY ESTOPPEL OR OTHERWISE, TO ANY INTELLECTUAL PROPERTY RIGHTS IS GRANTED BY THIS DOCUMENT. EXCEPT AS PROVIDED IN INTEL S TERMS AND CONDITIONS OF SALE FOR SUCH PRODUCTS, INTEL ASSUMES NO LIABILITY WHATSOEVER AND INTEL DISCLAIMS ANY EXPRESS OR IMPLIED WARRANTY, RELATING TO SALE AND/OR USE OF INTEL PRODUCTS INCLUDING LIABILITY OR WARRANTIES RELATING TO FITNESS FOR A PARTICULAR PURPOSE, MERCHANTABILITY, OR INFRINGEMENT OF ANY PATENT, COPYRIGHT OR OTHER INTELLECTUAL PROPERTY RIGHT. A "Mission Critical Application" is any application in which failure of the Intel Product could result, directly or indirectly, in personal injury or death. SHOULD YOU PURCHASE OR USE INTEL S PRODUCTS FOR ANY SUCH MISSION CRITICAL APPLICATION, YOU SHALL INDEMNIFY AND HOLD INTEL AND ITS SUBSIDIARIES, SUBCONTRACTORS AND AFFILIATES, AND THE DIRECTORS, OFFICERS, AND EMPLOYEES OF EACH, HARMLESS AGAINST ALL CLAIMS COSTS, DAMAGES, AND EXPENSES AND REASONABLE ATTORNEYS' FEES ARISING OUT OF, DIRECTLY OR INDIRECTLY, ANY CLAIM OF PRODUCT LIABILITY, PERSONAL INJURY, OR DEATH ARISING IN ANY WAY OUT OF SUCH MISSION CRITICAL APPLICATION, WHETHER OR NOT INTEL OR ITS SUBCONTRACTOR WAS NEGLIGENT IN THE DESIGN, MANUFACTURE, OR WARNING OF THE INTEL PRODUCT OR ANY OF ITS PARTS. Intel may make changes to specifications and product descriptions at any time, without notice. Designers must not rely on the absence or characteristics of any features or instructions marked reserved or undefined. Intel reserves these for future definition and shall have no responsibility whatsoever for conflicts or incompatibilities arising from future changes to them. The information here is subject to change without notice. Do not finalize a design with this information. Intel software products are copyrighted by and shall remain the property of Intel Corporation. Use, duplication, or disclosure is subject to restrictions stated in Intel s Software License Agreement, or in the case of software delivered to the government, in accordance with the software license agreement as defined in FAR 52.227-7013. The products described in this document may contain design defects or errors known as errata which may cause the product to deviate from published specifications. Current characterized errata are available on request. The code names presented in this document are only for use by Intel to identify products, technologies, or services in development that have not been made commercially available to the public, i.e., announced, launched, or shipped. They are not commercial names for products or services and are not intended to function as trademarks. Contact your local Intel sales office or your distributor to obtain the latest specifications and before placing your product order. Copies of documents which have an order number and are referenced in this document, or other Intel literature may be obtained by calling 1-800-548-4725 or by visiting Intel s website at http://www.intel.com/design/literature.htm. Intel processor numbers are not a measure of performance. Processor numbers differentiate features within each processor family, not across different processor families. See http://www.intel.com/products/processor_number for details. Intel is a trademark of Intel Corporation in the US and other countries. * Other brands and names may be claimed as the property of others. Copyright 2015 Intel Corporation. All rights reserved. Intel Cache Acceleration Software (Intel CAS) for Linux* v2.9 (GA) Release Notes June 2015 2 Document Number: 328497-010
Contents 1 Release Description... 5 1.1 Features... 5 1.2 Supported SSD drives... 5 1.3 Limitations... 5 1.4 Supported platforms... 7 2 3 Known Issues... 8 Resolved Issues... 10 Tables Table 1-1 Supported platforms... 7 Table 1-2 Supported hypervisor/os combinations... 7 Table 2-1 Known issues... 8 Table 3-1 Resolved issues...10 June 2015 Release Notes Document Number: 328497-010 3
Revision History Revision Description Date 001B Initial Beta release of document. January 2013 001 Initial public release of document. February 2013 002 Updates for v2.1 May 2013 003 Updates for v2.5 August 2013 004 Updates for v2.6 December 2013 005 Updates for v2.6.1 April 2014 006 Updates for v2.7 May 2014 007 Updates for v2.7 GA July 2014 008 Updates for v2.7.1 GA October 2014 009 Updates for v2.8 GA December 2014 010 Updates for v2.9 GA June 2015 Release Notes June 2015 4 Document Number: 328497-010
Release Description 1 Release Description This document describes extensions and deviations from the release functionality described in the Administrator Guide. 1.1 Features The new features of are: Intel CAS for Linux* will now install and compile from source on any distro This enables installation on non-validated distros. The software will continue to be validated on the most commonly used distros. Requests for bug fixes for non-validated distros or adding a distro to official validation can be submitted through the Intel Support Center. Intel CAS for Linux* will now automatically recompile from source via DKMS upon any kernel update. Trial period extended from 30 days to 120 days. Added progress bar when performing long cache management operations (eg., cache flush) Added ability to interrupt long cache management operations Various software changes to improve overall caching performance Added support for RHEL* 6.6 and CentOS 6.6 Bug fixes from v2.8. IMPORTANT: Please note the following changes and update any user-created scripts accordingly: --strict-mode obsoleted: This command-line option will be removed in the next software release. The --strict-mode option has been obsoleted from the --start-cache command. Strict mode is no longer needed as software improvements have made normal caching operations equally as data safe. --no-data-flush obsoleted from start-cache command: This option will be removed in the next software release. In previous releases, the user had to specify this parameter both when starting and stopping the cache in order for it to have an effect. This behavior has been optimized so that the user only needs to specify --no-data-flush when stopping the cache. 1.2 Supported SSD drives Intel CAS for Linux* is validated on the following Intel SSD Data Center Family devices: Intel SSD DC S3700 Series Intel SSD DC P3700 Series Note: Also supports any PCIe*, SAS, or SATA SSD that is supported by the OS platform (see Table 1-1), and can be direct attached, expander attached, or attached via SAN (with a single worker). 1.3 Limitations The release has the following known limitations: Linux file systems with less than 4096 byte (4KiB) block sizes may encounter less than ideal performance when workload mix has a high percentage of writes in write-back mode. An ext3 file system is limited to 16 TiB max core drive capacity. (Note that this is an intrinsic limitation of the ext3 file system, not an Intel CAS limit.) June 2015 Release Notes Document Number: 328497-010 5
Release Description When using Intel SSD 910 Series devices as cache, performance may be slower for partitioned disks. Use raw disks to avoid this issue. Partitioning of an intelcas virtual block device is not supported. If partitioning is desired, the primary storage should be partitioned prior to enabling caching. For VMs, cache can only be set up and accessed from the guest OS. Paravirtualized drivers are not supported. System sleep (S3) and hibernation (S4) power states and resumption from these states are not supported. Hot-plugging of either core or cache drives is not supported. For best performance, it is recommended to use the noop IO scheduler on the cache device (SSD). NUMA node IO transfers can result in performance degradation on multi-cpu platforms with high number of worker threads, if the threads send IO to a CPU that is not directly attached to the PCIe device that is the target of the IO. This is a known limitation of multi-cpu platform architecture and not of Intel CAS. Intel CAS for Linux does not provide support for Write Barrier requests. Starting with Intel CAS for Linux v2.9 and later, support is provided for FLUSH and FUA commands. Some older distros (eg. SLES11SP1) only use Write Barrier and not FLUSH/FUA. Recommendation is to update to modern distro with FLUSH/FUA support to avoid potential data corruption. Release Notes June 2015 6 Document Number: 328497-010
Release Description 1.4 Supported platforms Table 1-1 lists the platforms for 64-bit processors Intel Cache Acceleration Software (Intel CAS) for Linux* v2.9 (GA) supports. Table 1-1 Supported platforms Platform Kernel Red Hat* Enterprise Linux* (RHEL*) 5.11 x86_64, Kernel 2.6.18-400.1.1 Red Hat* Enterprise Linux* (RHEL*) 6.6 x86_64, Kernel 2.6.32-504.3.3 Red Hat* Enterprise Linux* (RHEL*) 7.0 x86_64, Kernel 3.10.0-123.13.2 SUSE* Linux* Enterprise Server (SLES*) Version 11 SP1 x86_64, Kernel 2.6.32.59.0.17.1 SUSE* Linux* Enterprise Server (SLES*) Version 11 SP2 x86_64, Kernel 3.0.101-0.7.29.1 SUSE* Linux* Enterprise Server (SLES*) Version 11 SP3 x86_64, Kernel 3.0.101-0.47.52.1 CentOS* 6.6 x86_64, Kernel 2.6.32-504.3.3 Other distros Intel CAS v2.9 will install and compile from source on other distros and other kernels, but the user may be required to reproduce any issues on a validated distro & kernel to receive support. Other kernels Note: The recent Kernel Stack Segment Vulnerability (CVE-2014-9322) kernel update security patch upgrades distro versions RHEL 5.x5.11, RHEL 6.xRHEL 6.6, and CentOS 6.x6.6. Validation testing has been discontinued for older unpatched versions of these distros. If you have an older distro version, please apply the kernel update security patch prior to installing Intel CAS. Table 1-2 lists the hypervisor/os combinations Intel Cache Acceleration Software (Intel CAS) for Linux* v2.9 (GA) supports. Note: For core devices (HDDs) accelerated by Intel CAS with libvirt+ KVM, write-through mode needs to be selected to run VMs properly. Table 1-2 Supported hypervisor/os combinations Hypervisor RHEL* 5.11 RHEL* 6.6-7.0, CentOS 6.6 SLES*11 SP1-SP3 Notes Xen* Not supported. 1 Supported as guest. Supported as guest. KVM* Not supported. 1 Supported as guest. Supported as guest. VMWare* Not supported. 1 Supported as guest. Supported as guest. Paravirtualized drivers are not supported. 1. Not supported due to OS limitations and instability observed in a virtual environment. June 2015 Release Notes Document Number: 328497-010 7
Known Issues 2 Known Issues Table 2-1 lists known issues in this release. Table 2-1 Known issues Reference Description Impact/status/workaround CASL-13893 CASL-13958 CASL-14241 CASL-13899 CASL-13946 CASL-13947 CASL-13974 CASL-40766 (CASL-44685, CASL-50749) CASL-41189 (CASL-44686, CASL-50751) CASL-41045 (CASL-44687, CASL-50754) In a VM install, the installer does not support paravirtualized drivers in guest OSes. Physically removing or attaching core or caching device does not work correctly if done while the system is running. Errors and long completion time when using CAS with Terasort on Hadoop & RHEL6.3 Virtual Machines: paravirtualization of guest OS makes intelcas setup impossible CWL does not support hibernate power state - S4 CWL does not support standby power state - S3 Intelcas does not resume from Frozen to Running state Low sequential performance in write-back after intensive random 4k blocks workload CAS performance degradation is observed in Write Back mode when eviction operations start during Vdbench run CAS Performance degradation on RHEL510 with disk IO scheduler different than noop Issue has been documented under limitations and is under investigation. Interim workaround: Forward physical drives to guest VMs before the guest OS is installed. Then install Intel CAS. Impact: CLI command casadm -L may still incorrectly display a removed device OR may not display a newly attached device. Status: Hot-plugging of either core or cache drive is not currently supported. Issue is under investigation. Issue has been documented under limitations and is under investigation. Same as CASL-16096. Paravirtualized drivers are not currently supported. Issue has been documented under limitations and is under investigation. Status: Sleep states are not currently supported. Issue has been documented under limitations and is under investigation. Status: Sleep states are not currently supported. Issue has been documented under limitations and is under investigation. Status: Hot-plugging of either core or cache drive is not currently supported. Issue is a known limitation and is under investigation. Issue is a known limitation and is under investigation. Issue is under investigation. Status: Issue occurs on older RHEL 5.x with older kernel 2.6.18 with specific IO scheduler. Interim workaround: Use different IO scheduler. Release Notes June 2015 8 Document Number: 328497-010
Known Issues Reference Description Impact/status/workaround CASL-43191 (CASL-50747) CASL-45526 (CASL-50753) Heavy performance drop when combining LMP with MIN metadata variant and many-toone configuration Vdbench terminates prematurely due to very low performance in LMP combined with many-to-one configuration Expected behavior. This is not a recommended configuration. Expected behavior. Same issue as CASL-43191. This is not a recommended configuration. June 2015 Release Notes Document Number: 328497-010 9
Resolved Issues 3 Resolved Issues Table 3-1 lists issues Intel has resolved or closed since the previous release. Table 3-1 Resolved issues Reference Description Impact/status/workaround CASL-50755 (CASL-45704) Data corruption in recovery mode on RHEL 5.11 and RHEL 6.5 CASL-59271 (CASL-64672) Cache state is sporadically innacurately described CASL-55907 (CASL-55738) If a file named intelcas1-1 exists in /dev, the intelcas1-1 device will not appear in /dev CASL-55909 (CASL-55725) CASL-51450 (CASL-51649) Cache cannot be stopped when one of its own caches is added as a core device (recursive loop) Kernel bug and restart after starting cache in wb mode. CASL-55664 (CASL-55666) Intel CAS does not start devices from configuration file after installation on systemd. Release Notes June 2015 10 Document Number: 328497-010