Thứ Năm, 25 tháng 5, 2017

Understanding Hadoop Clusters and the Network

This article is Part 1 in series that will take a closer look at the architecture and methods of a Hadoop cluster, and how it relates to the network and server infrastructure. The content presented here is largely based on academic work and conversations I’ve had with customers running real production clusters. If you run production Hadoop clusters in your data center, I’m hoping you’ll provide your valuable insight in the comments below. Subsequent articles to this will cover the server and network architecture options in closer detail. Before we do that though, lets start by learning some of the basics about how a Hadoop cluster works. OK, let’s get started!
Hadoop Server Roles
The three major categories of machine roles in a Hadoop deployment are Client machines, Masters nodes, and Slave nodes. The Master nodes oversee the two key functional pieces that make up Hadoop: storing lots of data (HDFS), and running parallel computations on all that data (Map Reduce). The Name Node oversees and coordinates the data storage function (HDFS), while the Job Tracker oversees and coordinates the parallel processing of data using Map Reduce. Slave Nodes make up the vast majority of machines and do all the dirty work of storing the data and running the computations. Each slave runs both a Data Node and Task Tracker daemon that communicate with and receive instructions from their master nodes. The Task Tracker daemon is a slave to the Job Tracker, the Data Node daemon a slave to the Name Node.
Client machines have Hadoop installed with all the cluster settings, but are neither a Master or a Slave. Instead, the role of the Client machine is to load data into the cluster, submit Map Reduce jobs describing how that data should be processed, and then retrieve or view the results of the job when its finished. In smaller clusters (~40 nodes) you may have a single physical server playing multiple roles, such as both Job Tracker and Name Node. With medium to large clusters you will often have each role operating on a single server machine.
In real production clusters there is no server virtualization, no hypervisor layer. That would only amount to unnecessary overhead impeding performance. Hadoop runs best on Linux machines, working directly with the underlying hardware. That said, Hadoop does work in a virtual machine. That’s a great way to learn and get Hadoop up and running fast and cheap. I have a 6-node cluster up and running in VMware Workstation on my Windows 7 laptop.

Hadoop Cluster

Thứ Năm, 11 tháng 5, 2017

How to show device on linux

lspci -nnk

02:00.0 RAID bus controller [0104]: LSI Logic / Symbios Logic MegaRAID SAS 2108 [Liberator] [1000:0079] (rev 05)
 Subsystem: Intel Corporation RAID Controller RS2BL040 [8086:9260]
 Kernel driver in use: megaraid_sas
 Kernel modules: megaraid_sas

lspci -vmmnn

Slot: 02:00.0
Class: RAID bus controller [0104]
Vendor: LSI Logic / Symbios Logic [1000]
Device: MegaRAID SAS 2108 [Liberator] [0079]
SVendor: Intel Corporation [8086]
SDevice: RAID Controller RS2BL040 [9260]
Rev: 05

Thứ Tư, 12 tháng 4, 2017

Iprables example

*filter
:INPUT ACCEPT [0:0]
:FORWARD ACCEPT [0:0]
:OUTPUT ACCEPT [0:0]
:RH-Firewall-1-INPUT - [0:0]
-A INPUT -p tcp -m state --state NEW -m tcp --dport 21 -j DROP
-A INPUT -p tcp -m state --state NEW -m tcp --dport 80 -j DROP
-A INPUT -j RH-Firewall-1-INPUT
-A RH-Firewall-1-INPUT -i lo -j ACCEPT
-A RH-Firewall-1-INPUT -p icmp --icmp-type any -j ACCEPT
-A RH-Firewall-1-INPUT -p 50 -j ACCEPT
-A RH-Firewall-1-INPUT -p 51 -j ACCEPT
-A RH-Firewall-1-INPUT -p udp --dport 5353 -d 224.0.0.251 -j ACCEPT
-A RH-Firewall-1-INPUT -p udp -m udp --dport 631 -j ACCEPT
-A RH-Firewall-1-INPUT -p tcp -m tcp --dport 631 -j ACCEPT
-A RH-Firewall-1-INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT
-A RH-Firewall-1-INPUT -m state --state NEW -m tcp -p tcp --dport 21 -j ACCEPT
-A RH-Firewall-1-INPUT -m state --state NEW -m tcp -p tcp --dport 22 -j ACCEPT
-A RH-Firewall-1-INPUT -m state --state NEW -m udp -p udp --dport 53 -j ACCEPT
-A RH-Firewall-1-INPUT -m state --state NEW -m tcp -p tcp --dport 53 -j ACCEPT
-A RH-Firewall-1-INPUT -m state --state NEW -m tcp -p tcp --dport 80 -j ACCEPT
-A RH-Firewall-1-INPUT -m state --state NEW -m tcp -p tcp --dport 2049 -j ACCEPT
-A RH-Firewall-1-INPUT -m state --state NEW -m tcp -p tcp --dport 5900:5950 -j ACCEPT
-A RH-Firewall-1-INPUT -m state --state NEW -m tcp -p tcp --dport 8002 -j ACCEPT
-A RH-Firewall-1-INPUT -m state --state NEW -m tcp -p tcp --dport 8003 -j ACCEPT
-A RH-Firewall-1-INPUT -m state --state NEW -m tcp -p tcp --dport 8899 -j ACCEPT
-A RH-Firewall-1-INPUT -m state --state NEW -m tcp -p tcp --dport 7777 -j ACCEPT
-A RH-Firewall-1-INPUT -j REJECT --reject-with icmp-host-prohibited
COMMIT

Thứ Ba, 14 tháng 3, 2017

How to check Fibre Channel HBAs in Linux

Step-1: Determine the Manufacturer and Model of the HBAs.

Run the lspci command to list all PCI cards detected on the system.
# lspci | grep "Fibre Channel"
07:00.0 Fibre Channel: QLogic Corp. ISP2532-based 8Gb Fibre Channel to PCI Express HBA (rev 02)
0a:00.0 Fibre Channel: QLogic Corp. ISP2532-based 8Gb Fibre Channel to PCI Express HBA (rev 02)
The above output shows the system bus has detected two QLogic HBAs.

Step-2: Get the Vendor and Device IDs for the HBAs installed.

These can be obtained from the file /usr/share/hwdata/pci.ids
# vi /usr/share/hwdata/pci.ids
.....
1077  QLogic Corp.
 2532  ISP2532-based 8Gb Fibre Channel to PCI Express HBA
.....
The vendor id for QLogic is 1077 and the device id is 2532. You could confirm this using the lspci -nn command as shown below
# lspci -nn | grep "Fibre Channel"
07:00.0 Fibre Channel [0c04]: QLogic Corp. ISP2532-based 8Gb Fibre Channel to PCI Express HBA [1077:2532] (rev 02)
0a:00.0 Fibre Channel [0c04]: QLogic Corp. ISP2532-based 8Gb Fibre Channel to PCI Express HBA [1077:2532] (rev 02)

Step-3: Check if the driver modules are installed.

This can be done by searching the list of available modules. (Replace 2.6.18-308.el5PAE with your kernel version in the command below)
# grep 1077 /lib/modules/2.6.18-308.el5PAE/modules.* | grep 2532
/lib/modules/2.6.18-308.el5PAE/modules.alias:alias pci:v00001077d00002532sv*sd*bc*sc*i* qla2xxx
/lib/modules/2.6.18-308.el5PAE/modules.pcimap:qla2xxx              0x00001077 0x00002532 0xffffffff 0xffffffff 0x00000000 0x00000000 0x0
The above output shows that this HBA is supported by the module qla2xxx

Step-4: Check if the drivers for these HBAs are loaded in the kernel.

The lsmod command will list the currently loaded kernel modules
# lsmod | grep qla2xxx
qla2xxx              1205905  0
scsi_transport_fc      44745  1 qla2xxx
scsi_mod              144277  16 be2iscsi, ib_iser, iscsi_tcp, bnx2i, libcxgbi, libiscsi2, scsi_transport_iscsi2, scsi_dh, sr_mod, sg, usb_storage, qla2xxx, scsi_transport_fc, libata,cciss, sd_mod
The output shows the module qla2xxx is loaded by the kernel. If you don't see any output for lsmod command then you can load the module using modprobe command
# modprobe -v qla2xxx

Step-5: Getting detailed information

You can find detailed information about the fibre channel adapters in the location /sys/class/fc_host/
# ll /sys/class/fc_host/
drwxr-xr-x 3 root root 0 Feb  5 11:28 host3
drwxr-xr-x 3 root root 0 Feb  5 11:28 host4
The directories host3 and host4 in the example above contains information specific to each adapter like node name (WWN), port name (WWN), type, speed,state etc.,
An easier way to get this information is to use the systool command.
# systool -c fc_host
Class = "fc_host"
  Class Device = "host3"
    Device = "host3"
  Class Device = "host4"
    Device = "host4"
The -v option gives you detailed output
# systool -c fc_host -v host3
Class = "fc_host"

 Class Device = "host3"
 Class Device path = "/sys/class/fc_host/host3"
   fabric_name         = "0x50014380272531e9"
   issue_lip           = <store method only>
   node_name           = "0x50014380281412e9"
   port_id             = "0x0000e8"
   port_name           = "0x50014380281412e8"
   port_state          = "Online"
   port_type           = "LPort (private loop)"
   speed               = "8 Gbit"
   supported_classes   = "Class 3"
   supported_speeds    = "1 Gbit, 2 Gbit, 4 Gbit, 8 Gbit"
   symbolic_name       = "HPAK344A FW:v5.06.03 DVR:v8.03.07.09.05.08-k"
   system_hostname     = ""
   tgtid_bind_type     = "wwpn (World Wide Port Name)"
   uevent              = <store method only>

   Device = "host3"
   Device path = "/sys/devices/pci0000:00/0000:00:01.0/0000:07:00.0/host3"
     edc               = <store method only>
     fw_dump           =
     nvram             = "ISP "
     optrom_ctl        = <store method only>
     optrom            =
     reset             = <store method only>
     sfp               = ""
     uevent            = <store method only>
     vpd               = "&" 
 

How to scan new FC LUNS and SCSI disks in Linux ?

1.First find out how many disks are visible in “fdisk -l” .
# fdisk -l 2>/dev/null | egrep '^Disk' | egrep -v 'dm-' | wc -l
 
2.Find out how many host bus adapter configured in the Linux box.you can use “systool -fc_host -v” to verify available FC in the system.
# ls /sys/class/fc_host
host0  host1
In this case,you need to scan host0 & host1 HBA.


3.If the system virtual memory is too low ,then do not proceed further.If you have enough free virtual memory,then you can proceed with below command to scan new LUNS.
# echo "1" > /sys/class/fc_host/host0/issue_lip
# echo "- - -" > /sys/class/scsi_host/host0/scan
# echo "1" > /sys/class/fc_host/host1/issue_lip
# echo "- - -" > /sys/class/scsi_host/host1/scan
Note: You need to monitor the “issue_lip” in /var/log/messages to determine when the scan will complete.This operation is an asynchronous operation.

4.Verify if the new LUN is visible or not by counting the available disks.
# fdisk -l 2>/dev/null | egrep '^Disk' | egrep -v 'dm-' | wc -l
If any new LUNS added ,then you can see more count is more then before scanning the LUNS.

 

 

Thứ Hai, 13 tháng 3, 2017

Some problems with mysql & mariadb

MySQL max_open_files more than 1024


Edit /etc/security/limits.conf and add the following lines
mysql soft nofile 65535
mysql hard nofile 65535

 Edit file /usr/lib/systemd/system/mysqld.service ( /usr/lib/systemd/system/mariadb.service  ) and /etc/systemd/system/mariadb.service.d/migrated-from-my.cnf-settings.conf 

Add at end:

LimitNOFILE=65535
LimitNPROC=65535

Chủ Nhật, 12 tháng 3, 2017

Key VMware vSphere -vCenter

   1. Key VMware vSphere 5.x Enterprise Plus Unlimited CPU :


JU2HK-4HH05-JZA89-J1CQP-1A2JW
4F47K-6EH47-RZW90-ZH252-C2J45
0U25N-6W305-JZTL0-FK2QM-3CFPC
1F6HF-4824J-GZXH0-D225H-8AUN5
HA4EU-D231L-ZZ5N8-3HA7M-A3TQ2



    2. Key VMware vSphere 5.x Enterprise Plus Unlimited VM :


5U6HE-6YJ86-DZ798-1LCZH-12YMH
4Y295-6W00L-6Z5K0-DK95K-8C6H4
1A0MR-08156-MZZ90-KL95M-32U7R
NU2P3-6D113-UZH29-Q0AN6-8AZ1G
1F02R-8H15M-RZ8C1-K10QH-9A3LL

 3. Vmware vSphere 6 Standard)

JA08H-6AJ03-H80G8-WT2Z0-0F06F
JU2D0-2FK13-088Q9-J93X0-928H2
JF092-FFLE6-H8940-Z22NP-06R1F
0V6XK-41J8L-M80P1-K39Z4-AYU2F
1Z6DK-FPK5J-H80U1-N12Z0-2P22D
4V042-DWK8J-084X9-CR0N0-9KU1F
5U4X0-DQ24K-485W0-LV2ZP-0YK5D
4C202-DXH12-H89U0-X39G0-1AK62

Thứ Năm, 9 tháng 3, 2017

Optimizing MySQL, Intermediate results

Configuration options, that made huge difference, comparing to the default values

  1. Query cache must be enabled and configured
query_cache_type=1        
query_cache_limit=1M
query_cache_size=256M
query_cache_min_res_unit=512
2. Various read and sort buffers must be set
key_buffer_size=128M
join_buffer_size=8M
myisam_sort_buffer_size=1M
sort_buffer_size=1M
read_buffer_size=4M 
read_rnd_buffer_size=4M
3. Set InnoDB tables to be stored each in separate file
innodb_file_per_table=1
4. Tweak MyISAM table
myisam_use_mmap=1