TUNING FOR ALL FLASH DEPLOYMENTS

Ceph Tuning and Best Practices for All Flash Intel® Xeon® Servers
Last updated: January 2017

TABLE OF CONTENTS

  1. Introduction
  2. Ceph Storage Hardware Guidelines
  3. Intel Tuning and Optimization Recommendations for Ceph
    1. Server Tuning
      1. Ceph Client Configuration
      2. Ceph Storage Node NUMA Tuning
    2. Memory Tuning
    3. NVMe SSD partitioning
    4. OS Tuning (must be done on all Ceph nodes)
      1. Kernel Tuning
      2. Filesystem considerations
      3. Disk read ahead
      4. OSD: RADOS
    5. RBD Tuning
    6. RGW: Rados Gateway Tuning
    7. Erasure Coding Tuning
  4. Appendix
  5. Sample Ceph.conf
  6. Sample sysctl.conf
  7. All-NVMe Ceph Cluster Tuning for MySQL workload
    1. Ceph.conf
    2. CBT YAML
    3. MySQL configuration file (my.cnf)
  8. Sample Ceph Vendor Solutions

INTRODUCTION

Ceph is a scalable, open source, software-defined storage offering that runs on commodity hardware. Ceph has been developed from the ground up to deliver object, block, and file system storage in a single software platform that is self-managing, self-healing and has no single point of failure. Because of its highly scalable, software defined storage architecture, can be a powerful storage solution to consider. 
This document covers Ceph tuning guidelines specifically for all flash deployments based on extensive testing by Intel with a variety of system, operating system and Ceph optimizations to achieve highest possible performance for servers with Intel® Xeon® processors and Intel® Solid State Drive Data Center (Intel® SSD DC) Series. Details of OEM system SKUs and Ceph reference architectures for targeted use-cases can be found on ceph.com web-site.

CEPH STORAGE HARDWARE GUIDELINES

  • Standard configuration is ideally suited for throughput oriented workloads (e.g., analytics, DVR). Intel® SSD Data Center P3700 series is recommended to achieve best possible performance while balancing the cost.
CPU Intel® Xeon® CPU E5-2650v4 or higher
Memory Minimum of 64 GB
NIC 10GbE
Disks 1x 1.6TB P3700 + 12 x 4TB HDDs (1:12 ratio) / P3700 as Journal and caching
Caching software Intel Cache Acceleration Software for read caching, option: Intel® Rapid Storage Technology enterprise/MD4.3
  • TCO optimized configuration provides best possible performance for performance centric workloads (e.g., database) while achieving the TCO with a mix of SATA SSDs and NVMe SSDs.
CPU Intel® Xeon® CPU E5-2690v4 or higher
Memory 128 GB or higher
NIC Dual 10GbE
Disks 1x 800GB P3700 + 4x S3510 1.6TB
  • IOPS optimized configuration provides best performance for workloads that demand low latency using all NVMe SSD configuration.
CPU Intel® Xeon® CPU E5-2699v4
Memory 128 GB or higher
NIC 1x 40GbE, 4x 10GbE
Disks 4 x P3700 2TB

INTEL TUNING AND OPTIMIZATION RECOMMENDATIONS FOR CEPH

SERVER TUNING

CEPH CLIENT CONFIGURATION

In a balanced system configuration both client and storage node configuration need to be optimized to get the best possible cluster performance. Care needs to be taken to ensure Ceph client node server has enough CPU bandwidth to achieve optimum performance. Below graph shows the end to end performance for different client CPU configurations for block workload.


Figure 1: Client CPU cores and Ceph cluster impact

CEPH STORAGE NODE NUMA TUNING

In order to avoid latency, it is important to minimize inter-socket communication between NUMA nodes to service client IO as fast as possible and avoid latency penalty. Based on extensive set of experiments conducted in Intel, it is recommended to pin Ceph OSD processes on the same CPU socket that has NVMe SSDs, HBAs and NIC devices attached.

 
Figure 2: NUMA node configuration and OSD assignment

*Ceph startup scripts need change with setaffinity=" numactl --membind=0 --cpunodebind=0 "

Below performance data shows best possible cluster throughput and lower latency when Ceph OSDs are partitioned by CPU socket to manage media connected to local CPU socket and network IO not going through QPI link.



Figure 3: NUMA node performance compared to default system configuration

MEMORY TUNING

Ceph default packages use tcmalloc. For flash optimized configurations, we found jemalloc providing best possible performance without performance degradation over time. Ceph supports jemalloc for the hammer release and later releases but you need to build with jemalloc option enabled.

Below graph in figure 4 shows how thread cache size impacts throughput. By tuning thread cache size, performance is comparable between TCMalloc and JEMalloc. However as shown in Figure 5 and Figure 6, TCMalloc performance degrades over time unlike JEMalloc.


Figure 4: Thread cache size impact over performance



Figure 5: TCMalloc performance in a running cluster over time



Figure 6: JEMalloc performance in a running cluster over time

NVME SSD PARTITIONING

It is not possible to take advantage of NVMe SSD bandwidth with single OSD. 4 is the optimum number of partitions per SSD drive that gives best possible performance.


Figure 7: Ceph OSD latency with different SSD partitions


Figure 8: CPU Utilization with different #of SSD partitions

OS TUNING

(must be done on all Ceph nodes)

KERNEL TUNING

1. Modify system control in /etc/sysctl.conf

# Kernel sysctl configuration file for Red Hat Linux
#
# For binary values, 0 is disabled, 1 is enabled.  See sysctl(8) and
# sysctl.conf(5) for more details.

# Controls IP packet forwarding
net.ipv4.ip_forward = 0

# Controls source route verification
net.ipv4.conf.default.rp_filter = 1

# Do not accept source routing
net.ipv4.conf.default.accept_source_route = 0

# Controls the System Request debugging functionality of the kernel
kernel.sysrq = 0

# Controls whether core dumps will append the PID to the core filename.
# Useful for debugging multi-threaded applications.
kernel.core_uses_pid = 1

# disable TIME_WAIT.. wait ..
net.ipv4.tcp_tw_recycle = 1
net.ipv4.tcp_tw_reuse = 1

# Controls the use of TCP syncookies
net.ipv4.tcp_syncookies = 0

# double amount of allowed conntrack
net.netfilter.nf_conntrack_max = 2621440
net.netfilter.nf_conntrack_tcp_timeout_established = 1800

# Disable netfilter on bridges.
net.bridge.bridge-nf-call-ip6tables = 0
net.bridge.bridge-nf-call-iptables = 0
net.bridge.bridge-nf-call-arptables = 0

# Controls the maximum size of a message, in bytes
kernel.msgmnb = 65536

# Controls the default maxmimum size of a mesage queue
kernel.msgmax = 65536

# Controls the maximum shared segment size, in bytes
kernel.shmmax = 68719476736

# Controls the maximum number of shared memory segments, in pages
kernel.shmall = 4294967296

 

2. IP jumbo frames

If your switch supports jumbo frames, then the larger MTU size is helpful. Our tests showed 9000 MTU improves Sequential Read/Write performance.

3. Set the Linux disk scheduler to cfq

FILESYSTEM CONSIDERATIONS

Ceph is designed to be mostly filesystem agnostic–the only requirement being that the filesystem supports extended attributes (xattrs). Ceph OSDs depend on the Extended Attributes (XATTRs) of the underlying file system for: a) Internal object state b) Snapshot metadata c) RGW Access control Lists etc. Currently XFS is the recommended file system. We recommend using big inode size (default inode size is 256 bytes) when creating the file system:

mkfs.xfs –i size=2048 /dev/sda1

Setting the inode size is important, as XFS stores xattr data in the inode. If the metadata is too large to fit in the inode, a new extent is created, which can cause quite a performance problem. Upping the inode size to 2048 bytes provides enough room to write the default metadata, plus a little headroom.
The following example mount options are recommended when using XFS:

mount -t xfs -o noatime,nodiratime,logbufs=8 /dev/sda1 /var/lib/Ceph/osd/Ceph-0

The following are specific recommendations for Intel SSD and Ceph.

mkfs.xfs -f -K -i size=2048 -s size=4096 /dev/md0
/bin/mount -o noatime,nodiratime/dev/md0 /data/mysql

DISK READ AHEAD

Read_ahead is the file prefetching technology used in the Linux operating system. It is a system call that loads a file's contents into the page cache. When a file is subsequently accessed, its contents are read from physical memory rather than from disk, which is much faster.

echo 2048 > /sys/block/${disk}/queue/read_ahead_kb  (default 128)
Per disk performance 128 512 Percentage
Sequential Read(MB/s) 1232 MB/s 3251 MB/s +163%
  • 6 nodes Ceph cluster, each have 20 OSD (750 GB * 7200 RPM. 2.5’’ HDD)

OSD: RADOS

Tuning have significant performance impact of Ceph storage system, there are hundreds of tuning knobs for swift. We will introduce some of the most important tuning settings.

  1. Large PG/PGP number (since Cuttlefish)
    We find using large PG number per OSD (>200) will improve the performance. Also this will ease the data distribution unbalance issue
    (default to 8)
ceph osd pool create testpool 8192 8192
  2. omap data on separate disks (since Giant)
    Mounting omap directory to some separate SSD will improve the random write performance. In our testing we saw a ~20% performance improvement.
  3. objecter_inflight_ops/objecter_inflight_op_bytes (since Cuttlefish)
    objecter_inflight_ops/objecter_inflight_op_bytes throttles tell objecter to throttle outgoing ops according its budget, objecter is responsible for send requests to OSD. By default tweak this parameter to 10x 
    (default to 1024/1024*1024*100)
objecter_inflight_ops = 10240
objecter_inflight_op_bytes = 1048576000
  4. ms_dispatch_throttle_bytes (since Cuttlefish)
    ms_dispatch_throttle_bytes throttle is to throttle dispatch message size for simple messenger, by default tweak this parameter to 10x. 
    ms_dispatch_throttle_bytes = 1048576000
  5. journal_queue_max_bytes/journal_queue_max_ops (since Cuttlefish)
    journal_queue_max_bytes/journal_queue_max_op throttles are to throttle inflight ops for journal, 
    If journal does not get enough budget for current op, it will block osd op thread, by default tweak this parameter to 10x.
    journal_queueu_max_ops = 3000
journal_queue_max_bytes = 1048576000
  6. filestore_queue_max_ops/filestore_queue_max_bytes (since Cuttlefish)
    filestore_queue_max_ops/filestore_queue_max_bytes throttle are used to throttle inflight ops for filestore, these throttles are checked before sending ops to journal, so if filestore does not get enough budget for current op, osd op thread will be blocked, by default tweak this parameter to 10x.
    filestore_queue_max_ops=5000
filestore_queue_max_bytes = 1048576000
  7. filestore_op_threads controls the number of filesystem operation threads that execute in parallel
    If the storage backend is fast enough and has enough queues to support parallel operations, it’s recommended to increase this parameter, given there is enough CPU head room.
    filestore_op_threads=6
  8. journal_max_write_entries/journal_max_write_bytes (since Cuttlefish)
    journal_max_write_entries/journal_max_write_bytes throttle are used to throttle ops or bytes for every journal write, tweaking these two parameters maybe helpful for small write, by default tweak these two parameters to 10x
    journal_max_write_entries = 5000
journal_max_write_bytes = 1048576000
  9. osd_op_num_threads_per_shard/osd_op_num_shards (since Firefly)
    osd_op_num_shards set number of queues to cache requests , osd_op_num_threads_per_shard is threads number for each queue, adjusting these two parameters depends on cluster.
    After several performance tests with different settings, we concluded that default parameters provide best performance.
  10. filestore_max_sync_interval (since Cuttlefish)
    filestore_max_sync_interval control the interval that sync thread flush data from memory to disk, by default filestore write data to memory and sync thread is responsible for flushing data to disk, then journal entries can be trimmed. Note that large filestore_max_sync_interval can cause performance spike. By default tweak this parameter to 10 seconds
    filestore_max_sync_interval = 10
  11. ms_crc_data/ms_crc_header (since Cuttlefish)
    Disable crc computation for simple messenger, this can reduce CPU utilization
  12. filestore_fd_cache_shards/filestore_fd_cache_size (since Firefly)
    filestore cache is map from objectname to fd, filestore_fd_cache_shards set number of LRU Cache, filestore_fd_cache_size is cache size, tweak these two parameter maybe reduce lookup time of fd
  13. Set debug level to 0 (since Cuttlefish)
    For an all-SSD Ceph cluster, set debug level for sub system to 0 will improve the performance. 
    debug_lockdep = 0/0
debug_context = 0/0
debug_crush = 0/0
debug_buffer = 0/0
debug_timer = 0/0
debug_filer = 0/0
debug_objecter = 0/0
debug_rados = 0/0
debug_rbd = 0/0
debug_journaler = 0/0
debug_objectcatcher = 0/0
debug_client = 0/0
debug_osd = 0/0
debug_optracker = 0/0
debug_objclass = 0/0
debug_filestore = 0/0
debug_journal = 0/0
debug_ms = 0/0
debug_monc = 0/0
debug_tp = 0/0
debug_auth = 0/0
debug_finisher = 0/0
debug_heartbeatmap = 0/0
debug_perfcounter = 0/0
debug_asok = 0/0
debug_throttle = 0/0
debug_mon = 0/0
debug_paxos = 0/0
debug_rgw = 0/0

RBD TUNING

To help achieve low latency on their RBD layer, we suggest the following, in addition to the CERN tuning referenced in ceph.com.

  1. echo performance | tee /sys/devices/system/cpu/cpu*/cpufreq/scaling_governor /dev/null
  2. start each ceph-osd in dedicated cgroup with dedicated cpu cores (which should be free from any other load, even the kernel one like network interrupts)
  3. increase “filestore_omap_header_cache_size” • “filestore_fd_cache_size” , for better caching (16MB for each 500GB of storage)
    For disk entry in libvirt put address to all three ceph monitors.

RGW: RADOS GATEWAY TUNING

  1. Disable usage/access log (since Cuttlefish)
    rgw enable ops log = false
rgw enable usage log = false
log file = /dev/null

    We find disabling usage/access log improves the performance.
  2. Using large cache size (since Cuttlefish)
    rgw cache enabled = true
rgw cache lru size = 100000

    Caching the hot objects improves the GET performance.
  3. Using larger PG split/merge value. (since Firefly)
    filestore_merge_threshold = 500
filestore_split_multiple = 100

    We find PG split/merge will introduce a big overhead. Using a large value would postpone the split/merge behavior. This will help the case where lots of small files are stored in the cluster.
  4. Using load balancer with multiple RGW instances (since Cuttlefish)

    We’ve found that the RGW has some scalability issues at present. With a single RGW instance the performance is poor. Running multiple RGW instances with a load balancer (e.g., Haproxy) will greatly improve the throughput.
  5. Increase the number of Rados handlers (since Hammer)
    Since Hammer it’s able to using multiple number of Rados handlers per RGW instances. Increasing this value should improve the performance.
  6. Using Civetweb frontend (since Giant)
    Before Giant, Apache + Libfastcgi were the recommended settings. However libfastcgi still use the very old ‘select’ mode, which is not able to handle large amount of concurrent IO in our testing. Using Civetweb frontend would help to improve the stability.
    rgw frontends =civetweb port=80
  7. Moving bucket index to SSD (since Giant)
    Bucket index updating maybe some bottleneck if there’s millions of objects in one single bucket. We’ve find moving the bucket index to SSD storage will improve the performance.
  8. Bucket Index Sharding (since Hammer)
    We’ve find the bucket index sharding is a problem if there’s large amount of objects inside one bucket. However the index listing speed may be impacted.

ERASURE CODING TUNING

  1. Use larger stripe width 
    The default erasure code stripe size (4K) is not optimal, We find using a bigger value (64K) will reduce the CPU% a lot (10%+)
    osd_pool_erasure_code_stripe_width = 65536
  2. Use mid-sized K
    For the Erasure Code algorithms, we find using some mid-sized K value would bring balanced results between throughput and CPU%. We recommend to use 10+4 or 8+2 mode

APPENDIX

SAMPLE CEPH.CONF

[global]
fsid = 35b08d01-b688-4b9a-947b-bc2e25719370
mon_initial_members = gw2
mon_host = 10.10.10.105
filestore_xattr_use_omap = true
auth_cluster_required = none
auth_service_required = none
auth_client_required = none
debug_lockdep = 0/0
debug_context = 0/0
debug_crush = 0/0
debug_buffer = 0/0
debug_timer = 0/0
debug_filer = 0/0
debug_objecter = 0/0
debug_rados = 0/0
debug_rbd = 0/0
debug_journaler = 0/0
debug_objectcatcher = 0/0
debug_client = 0/0
debug_osd = 0/0
debug_optracker = 0/0
debug_objclass = 0/0
debug_filestore = 0/0
debug_journal = 0/0
debug_ms = 0/0
debug_monc = 0/0
debug_tp = 0/0
debug_auth = 0/0
debug_finisher = 0/0
debug_heartbeatmap = 0/0
debug_perfcounter = 0/0
debug_asok = 0/0
debug_throttle = 0/0
debug_mon = 0/0
debug_paxos = 0/0
debug_rgw = 0/0
[mon]
mon_pg_warn_max_per_osd=5000
mon_max_pool_pg_num=106496
[client]
rbd cache = false
[osd]
osd mkfs type = xfs
osd mount options xfs = rw,noatime,,nodiratime,inode64,logbsize=256k,delaylog
osd mkfs options xfs = -f -i size=2048
filestore_queue_max_ops=5000
filestore_queue_max_bytes = 1048576000
filestore_max_sync_interval = 10
filestore_merge_threshold = 500
filestore_split_multiple = 100
osd_op_shard_threads = 8
journal_max_write_entries = 5000
journal_max_write_bytes = 1048576000
journal_queueu_max_ops = 3000
journal_queue_max_bytes = 1048576000
ms_dispatch_throttle_bytes = 1048576000
objecter_inflight_op_bytes = 1048576000
public_network = 10.10.10.100/24
cluster_network = 10.10.10.100/24

[client.radosgw.gw2-1]
host = gw2
keyring = /etc/ceph/ceph.client.radosgw.keyring
rgw cache enabled = true
rgw cache lru size = 100000
rgw socket path = /var/run/ceph/ceph.client.radosgw.gw2-1.fastcgi.sock
rgw thread pool size = 256
rgw enable ops log = false
rgw enable usage log = false
log file = /dev/null
rgw frontends =civetweb port=80
rgw override bucket index max shards = 8

SAMPLE SYSCTL.CONF

fs.file-max = 6553600
net.ipv4.ip_local_port_range = 1024 65000
net.ipv4.tcp_fin_timeout = 20
net.ipv4.tcp_max_syn_backlog = 819200
net.ipv4.tcp_keepalive_time = 20
kernel.msgmni = 2878
kernel.sem = 256 32000 100 142
kernel.shmmni = 4096
net.core.rmem_default = 1048576
net.core.rmem_max = 1048576
net.core.wmem_default = 1048576
net.core.wmem_max = 1048576
net.core.somaxconn = 40000
net.core.netdev_max_backlog = 300000
net.ipv4.tcp_max_tw_buckets = 10000

ALL-NVME CEPH CLUSTER TUNING FOR MYSQL WORKLOAD

CEPH.CONF

[global]
        enable experimental unrecoverable data corrupting features = bluestore rocksdb
        osd objectstore = bluestore
        ms_type = async
        rbd readahead disable after bytes = 0
        rbd readahead max bytes = 4194304
        bluestore default buffered read = true
        auth client required = none
        auth cluster required = none
        auth service required = none
        filestore xattr use omap = true
        cluster network = 192.168.142.0/24, 192.168.143.0/24
        private network = 192.168.144.0/24, 192.168.145.0/24
        log file = /var/log/ceph/$name.log
        log to syslog = false
        mon compact on trim = false
        osd pg bits = 8
        osd pgp bits = 8
        mon pg warn max object skew = 100000
        mon pg warn min per osd = 0
        mon pg warn max per osd = 32768
        debug_lockdep = 0/0
        debug_context = 0/0
        debug_crush = 0/0
        debug_buffer = 0/0
        debug_timer = 0/0
        debug_filer = 0/0
        debug_objecter = 0/0
        debug_rados = 0/0
        debug_rbd = 0/0
        debug_ms = 0/0
        debug_monc = 0/0
        debug_tp = 0/0
        debug_auth = 0/0
        debug_finisher = 0/0
        debug_heartbeatmap = 0/0
        debug_perfcounter = 0/0
        debug_asok = 0/0
        debug_throttle = 0/0
        debug_mon = 0/0
        debug_paxos = 0/0
        debug_rgw = 0/0
        perf = true
        mutex_perf_counter = true
        throttler_perf_counter = false
        rbd cache = false
[mon]
        mon data =/home/bmpa/tmp_cbt/ceph/mon.$id
        mon_max_pool_pg_num=166496
        mon_osd_max_split_count = 10000
        mon_pg_warn_max_per_osd = 10000
[mon.a]
        host = ft02
        mon addr = 192.168.142.202:6789
[osd]
        osd_mount_options_xfs = rw,noatime,inode64,logbsize=256k,delaylog
        osd_mkfs_options_xfs = -f -i size=2048
        osd_op_threads = 32
        filestore_queue_max_ops=5000
        filestore_queue_committing_max_ops=5000
        journal_max_write_entries=1000
        journal_queue_max_ops=3000
        objecter_inflight_ops=102400
        filestore_wbthrottle_enable=false
        filestore_queue_max_bytes=1048576000
        filestore_queue_committing_max_bytes=1048576000
        journal_max_write_bytes=1048576000
        journal_queue_max_bytes=1048576000
        ms_dispatch_throttle_bytes=1048576000
        objecter_infilght_op_bytes=1048576000
        osd_mkfs_type = xfs
        filestore_max_sync_interval=10
        osd_client_message_size_cap = 0
        osd_client_message_cap = 0
        osd_enable_op_tracker = false
        filestore_fd_cache_size = 64
        filestore_fd_cache_shards = 32
        filestore_op_threads = 6

CBT YAML

cluster:
  user: "bmpa" 
  head: "ft01" 
  clients: ["ft01", "ft02", "ft03", "ft04", "ft05", "ft06"]
  osds: ["hswNode01", "hswNode02", "hswNode03", "hswNode04", "hswNode05"]
  mons:
   ft02:
     a: "192.168.142.202:6789" 
osds_per_node: 16
  fs: xfs
  mkfs_opts: '-f -i size=2048 -n size=64k'
  mount_opts: '-o inode64,noatime,logbsize=256k'
  conf_file: '/home/bmpa/cbt/ceph.conf'
  use_existing: False
  newstore_block: True
  rebuild_every_test: False
  clusterid: "ceph" 
iterations: 1
  tmp_dir: "/home/bmpa/tmp_cbt" 
pool_profiles:
    2rep:
      pg_size: 8192
      pgp_size: 8192
      replication: 2
benchmarks:
  librbdfio:
    time: 300
    ramp: 300
    vol_size: 10
    mode: ['randrw']
    rwmixread: [0,70,100]
    op_size: [4096]
    procs_per_volume: [1]
    volumes_per_client: [10]
    use_existing_volumes: False
    iodepth: [4,8,16,32,64,128]
    osd_ra: [4096]
    norandommap: True
    cmd_path: '/usr/local/bin/fio'
    pool_profile: '2rep'
    log_avg_msec: 250

MYSQL CONFIGURATION FILE (MY.CNF)

[client]
port            = 3306
socket          = /var/run/mysqld/mysqld.sock
[mysqld_safe]
socket          = /var/run/mysqld/mysqld.sock
nice            = 0
[mysqld]
user            = mysql
pid-file        = /var/run/mysqld/mysqld.pid
socket          = /var/run/mysqld/mysqld.sock
port            = 3306
datadir         = /data
basedir         = /usr
tmpdir          = /tmp
lc-messages-dir = /usr/share/mysql
skip-external-locking
bind-address            = 0.0.0.0
max_allowed_packet      = 16M
thread_stack            = 192K
thread_cache_size       = 8
query_cache_limit       = 1M
query_cache_size        = 16M
log_error = /var/log/mysql/error.log
expire_logs_days        = 10
max_binlog_size         = 100M
performance_schema=off
innodb_buffer_pool_size = 25G
innodb_flush_method = O_DIRECT
innodb_log_file_size=4G
thread_cache_size=16
innodb_file_per_table
innodb_checksums = 0
innodb_flush_log_at_trx_commit = 0
innodb_write_io_threads = 8
innodb_page_cleaners= 16
innodb_read_io_threads = 8
max_connections = 50000
[mysqldump]
quick
quote-names
max_allowed_packet      = 16M
[mysql]
!includedir /etc/mysql/conf.d/

SAMPLE CEPH VENDOR SOLUTIONS

The following are pointers to Ceph solutions, but this list is not comprehensive:

Notices:
Copyright © 2016 Intel Corporation. All rights reserved
Intel, the Intel logo, Intel Atom, Intel Core, and Intel Xeon are trademarks of Intel Corporation in the U.S. and/or other countries. *Other names and brands may be claimed as the property of others.
Results have been estimated based on internal Intel analysis and are provided for informational purposes only. Any difference in system hardware or software design or configuration may affect actual performance.
Intel® Hyper-Threading Technology available on select Intel® Core™ processors. Requires an Intel® HT Technology-enabled system. Consult your PC manufacturer. Performance will vary depending on the specific hardware and software used. For more information including details on which processors support HT Technology, visit http://www.intel.com/info/hyperthreading.
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http://tracker.ceph.com/projects/ceph/wiki/Tuning_for_All_Flash_Deployments

posted on 2017-08-28 09:38  allcloud  阅读(1431)  评论(0)  编辑  收藏  举报

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