Cohesity

If you haven’t heard of Cohesity, it’s time you do. If you have heard Cohesity is a backup company, that is good but we do more.

In a legacy setup, you have the following solutions from multiple vendors or at least they are different products from the same vendor.

  • Backup software
  • Storage to store the backup
  • Dedupe appliance
  • Archival
  • Cloud connector etc…

Cohesity does all of this in one box. When you buy Cohesity, you have all of these. Additionally, we do file and object shortage.

When you have all the data, what can you do with it? Analytics and Test/Dev.

Cohesity Cluster

What’s a Cohesity Cluster? A Cohesity Cluster consists of a bunch of nodes and provides the services mentioned above.

Cohesity Nodes

A Cohesity node consists of a computer node with SSD(s) and HDDs. CentOS 7x based OS and Cohesity software running on it.

Product types

Currently, the bulk of the install base is on our own hardware appliance. Customers can choose to run it in HP and Cisco hardware too.

We have Virtual Edition for VMware vSphere and Hyper-V. They are available as ova and vhd format respectively. Maybe we will have one for AHV in the future.

If you want to run Cohesity in the Cloud (on someone’s computer), why not? We have Cloud Edition for the three major Cloud providers.

Irrespective of the product type, the software remains the same. Once deployed, we use the same software package for an upgrade.

Cohesity is one platform with infinite possibilities.

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How to check memory error count in Linux

We have 8 DIMMs, 4 on each controller in this system.

sudo dmidecode -t memory  |grep -A10 'Locator: DIMM' | grep Serial.Number | grep -v NO.DIMM
    Serial Number: E22C60A2
    Serial Number: E12C4EA2
    Serial Number: DD2C61A2
    Serial Number: E32C4EA2
    Serial Number: E32C53A2
    Serial Number: DE2C5DA2
    Serial Number: E02C50A2
    Serial Number: E22C65A2
sudo dmidecode -t memory  |grep -A10 'Locator: DIMM' | grep Serial.Number | grep -v NO.DIMM | wc -l
8

Correctable error count

ls  -l /sys/devices/system/edac/mc/mc*/csrow*/*ce_count
-r--r--r-- 1 root root 4096 Apr 21 01:48 /sys/devices/system/edac/mc/mc0/csrow0/ce_count .     - Correctable error count for this row
-r--r--r-- 1 root root 4096 Apr 21 01:48 /sys/devices/system/edac/mc/mc0/csrow0/ch0_ce_count   - Correctable error count for this channel
-r--r--r-- 1 root root 4096 Apr 21 01:48 /sys/devices/system/edac/mc/mc0/csrow0/ch1_ce_count
-r--r--r-- 1 root root 4096 Apr 21 01:48 /sys/devices/system/edac/mc/mc0/csrow0/ch2_ce_count
-r--r--r-- 1 root root 4096 Apr 21 01:48 /sys/devices/system/edac/mc/mc0/csrow0/ch3_ce_count
-r--r--r-- 1 root root 4096 Apr 21 01:48 /sys/devices/system/edac/mc/mc1/csrow0/ce_count
-r--r--r-- 1 root root 4096 Apr 21 01:48 /sys/devices/system/edac/mc/mc1/csrow0/ch0_ce_count
-r--r--r-- 1 root root 4096 Apr 21 01:48 /sys/devices/system/edac/mc/mc1/csrow0/ch1_ce_count
-r--r--r-- 1 root root 4096 Apr 21 01:48 /sys/devices/system/edac/mc/mc1/csrow0/ch2_ce_count
-r--r--r-- 1 root root 4096 Apr 21 01:48 /sys/devices/system/edac/mc/mc1/csrow0/ch3_ce_count

There are no correctable errors.

cat /sys/devices/system/edac/mc/mc*/csrow*/*ce_count
0
0
0
0
0
0
0
0
0
0

Uncorrectable errors

cat  /sys/devices/system/edac/mc/mc*/csrow*/ue_count
0
0

This his provided by a kernel module edac (Error Detection and Correction)

lsmod  | grep edac
sb_edac                27005  0
edac_core              57973  1 sb_edac

There is a utility called edac-util.
http://fibrevillage.com/sysadmin/240-how-to-identify-defective-dimm-from-edac-error-on-linux-2

Good reference
http://www.admin-magazine.com/Articles/Monitoring-Memory-Errors

Remove interface from a bond

[cohesity@benjamin_ve ~]$ cat /proc/net/bonding/bond0 | grep Int
MII Polling Interval (ms): 100
Slave Interface: eno16784128
Slave Interface: eno33555456
[cohesity@benjamin_ve ~]$ sudo ifenslave -d bond0 eno33555456
[cohesity@benjamin_ve ~]$ cat /proc/net/bonding/bond0 | grep Int
MII Polling Interval (ms): 100
Slave Interface: eno16784128
[cohesity@benjamin_ve ~]$

Delete host key from known_hosts file

I normally delete the known_hosts file on my machine (not server) when I ssh to a server because the fingerprint has changed. You can delete host’s key as follows.

ssh-keygen -R hostname
# Host hostname found: line 6
/Users/benjaminr/.ssh/known_hosts updated.
Original contents retained as /Users/benjaminr/.ssh/known_hosts.old

Of course, you don’t want to simply do this unless you are aware something changed.