One of the lesser publicized but highly versatile tools in OneFS is the ‘isi get’ command line utility. It can often prove invaluable for generating a vast array of useful information about OneFS file system objects. In its most basic form, the command outputs this following information:

 

  • Protection policy
  • Protection level
  • Layout strategy
  • Write caching strategy
  • File name

 

For example:

 

# isi get /ifs/data/file2.txt

POLICY LEVEL     PERFORMANCE      COAL FILE

default             4+2/2     concurrency      on file2.txt

 

Here’s what each of these categories represents:

 

POLICY:  Indicates the requested protection for the object, in this case a text file. This policy field is displayed in one of three colors:

 

Requested Protection Policy

Description

Green

Fully protected

Yellow

Degraded protection under a mirroring policy

Red

Under-protection using FEC parity protection

 

LEVEL:  Displays the current actual on-disk protection of the object. This can be either FEC parity protection or mirroring. For example:

 

Protection  Level

Description

+1n

Tolerate failure of 1 drive OR 1 node (Not Recommended)

+2d:1n

Tolerate failure of 2 drives OR 1 node

+2n

Tolerate failure of 2 drives OR 2 nodes

+3d:1n

Tolerate failure of 3 drives OR 1 node

+3d:1n1d

Tolerate failure of 3 drives OR 1 node AND 1 drive

+3n

Tolerate failure of 3 drives or 3 nodes

+4d:1n

Tolerate failure of 4 drives or 1 node

+4d:2n

Tolerate failure of 4 drives or 2 nodes

+4n

Tolerate failure of 4 nodes

2x to 8x

Mirrored over 2 to 8 nodes, depending on configuration

 

PERFORMANCE:  Indicates the on-disk layout strategy, for example:

 

Data Access Setting

Description

On Disk Layout

Caching

Concurrency

Optimizes for current load on cluster, featuring many simultaneous clients. Recommended for mixed workloads.

Stripes data across the minimum number of drives required to achieve the configured data protection level.

Moderate prefetching

Streaming

Optimizes for streaming of a single file. For example, fast reading by a single client.

Stripes data across a larger number of drives.

Aggressive prefetching

Random

Optimizes for unpredictable access to a file. Performs almost no cache prefetching.

Stripes data across the minimum number of drives required to achieve the configured data protection level.

Little to no prefetching

 

COAL:  Indicates whether the Coalescer, OneFS’s NVRAM based write cache, is enabled. The coalescer provides failure-safe buffering to ensure that writes are efficient and read-modify-write operations avoided.

 

The isi get command also provides a number of additional options to generate more detailed information output. As such, the basic command syntax for isi get is as follows:

 

isi get {{[-a] [-d] [-g] [-s] [{-D | -DD | -DDC}] [-R] <path>}

| {[-g] [-s] [{-D | -DD | -DDC}] [-R] -L <lin>}}

 

Here’s the description for the various flags and options available for the command:

 

Command Option

Description

-a

Displays the hidden "." and ".." entries of each directory.

-d

Displays the attributes of a directory instead of the contents.

-g

Displays detailed information, including snapshot governance lists.

-s

Displays the protection status using words instead of colors.

-D

Displays more detailed information.

-DD

Includes information about protection groups and security descriptor owners and groups.

-DDC

Includes cyclic redundancy check (CRC) information.

-L <LIN>

Displays information about the specified file or directory. Specify as a file or directory LIN.

-O

Displays any logical overlay information and a compressed block count when viewing a file’s details.

-R

Displays information about the subdirectories and files of the specified directories.

 

The following command shows the detailed properties of a directory, /ifs/data. Note that the output has been truncated slightly to aid readability:


# isi get -D data 

POLICY   W LEVEL PERFORMANCE COAL ENCODING      FILE              IADDRS

default       4x/2 concurrency on  ˜- còÎ" v:shapes="Picture_x0020_10">  N/A ./ <1,36,268734976:512>, <1,37,67406848:512>, <2,37,269256704:512>, <3,37,336369152:512> ct: 1459203780 rt: 0 

*************************************************

* IFS inode: [ 1,36,268734976:512, 1,37,67406848:512, 2,37,269256704:512, 3,37,336369152:512 ]   ×ôë¸å ]ï¤Ý" v:shapes="Picture_x0020_2">

*************************************************

*  Inode Version:      6

*  Dir Version:        2

*  Inode Revision:     6

*  Inode Mirror Count: 4

*  Recovered Flag:     0

*  Restripe State:     0

*  Link Count:         3

*  Size:               54

*  Mode:               040777

*  Flags:              0xe0

*  Stubbed:            False

*  Physical Blocks:    0

*  LIN:                1:0000:0004 

*  Logical Size:       None

*  Shadow refs:        0

*  Do not dedupe:      0

*  Last Modified:      1461091982.785802190

*  Last Inode Change:  1461091982.785802190

*  Create Time:        1459203780.720209076

*  Rename Time:        0

*  Write Caching:      Enabled

*  Parent Lin          2

*  Parent Hash:        763857

*  Snapshot IDs:       None

*  Last Paint ID:      47

*  Domain IDs:         None

*  LIN needs repair:   False

*  Manually Manage:

*       Access         False

*       Protection     True

*  Protection Policy:  default

*  Target Protection:  4x

*  Disk pools:         policy any pool group ID -> data target z x410_136tb_1.6tb-ssd_256gb:32(32), metadata target x410_136tb_1.6tb-ssd_256gb:32(32)

*  SSD Strategy:       metadata-write  {

*  SSD Status:         complete

*  Layout drive count: 0

*  Access pattern: 0

*  Data Width Device List:

*  Meta Width Device List:

*

*  File Data (78 bytes):

*    Metatree Depth: 1

*  Dynamic Attributes (40 bytes):

        ATTRIBUTE                OFFSET SIZE

        New file attribute       0 23

        Isilon flags v2          23 3

        Disk pool policy ID      26 5

        Last snapshot paint time 31     9

*************************************************

 

*  NEW FILE ATTRIBUTES |

*  Access attributes:  active

*  Write Cache: on

*  Access Pattern:  concurrency

*  At_r: 0

*  Protection attributes:  active

*  Protection Policy:  default

  1. *  Disk pools:         policy any pool group ID 

*  SSD Strategy:       metadata-write

*

*************************************************

 

Here is what some of these lines indicate:            

 

Line number

Description

1

OneFS command to display the file system properties of a directory or file.

2

The directory's data access pattern is set to concurrency.

3

Write caching (coalescer) is turned on.

4

Inode on-disk locations

5

Primary LIN.

6

Indicates disk pools that the data and metadata are targeted to.

7

the SSD strategy is set to metadata-write.

8

Files that are added to the directory are governed by these settings, most of which can be changed by applying a file pool policy to the directory.

 

From the WebUI, a subset of the ‘isi get –D’ output is also available from the OneFS File Explorer. This can be accessed by browsing to File System > File System Explorer and clicking on ‘View Property Details’ for the file system object of interest.


One question that is frequently asked is how to find where a file's inodes live on the cluster. The ‘isi get -D’ command output makes this fairly straightforward to answer. Take the file /ifs/data/file1, for example:


# isi get -D /ifs/data/file1 | grep -i "IFS inode"

* IFS inode: [ 1,9,8388971520:512, 2,9,2934243840:512, 3,8,9568206336:512 ]


This shows the three inode locations for the file in the *,*,*:512 notation. Let’s take the first of these:


1,9,8388971520:512


From this, we can deduce the following:

 

  • The inode is on node 1, drive 9 (logical drive number).
  • The logical inode number is 8388971520.
  • It’s an inode block that’s 512 bytes in size (Note: OneFS data blocks are 8kB in size).


Another example of where isi get can be useful is in mapping between a file system object’s pathname and its LIN (logical inode number). This might be for translating a LIN returned by an audit logfile or job engine report into a valid filename, or finding an open file from vnodes output, etc.


For example, say you wish to know which configuration file is being used by the cluster’s DNS service:


1.  First, inspect the busy_vnodes output and filter for DNS:


# sysctl efs.bam.busy_vnodes | grep -i dns

vnode 0xfffff8031f28baa0 (lin 1:0066:0007) is fd 19 of pid 4812: isi_dnsiq_d

 

This, among other things, provides the LIN for the isi_dnsiq_d process.


2.  The output can be further refined to just the LIN address as such:


# sysctl efs.bam.busy_vnodes | grep -i dns | awk '{print $4}' | sed -E 's/\)//'

1:0066:0007


3.  This LIN address can then be fed into ‘isi get’ using the ‘-L’ flag, and a valid name and path for the file will be output:


# isi get -L `sysctl efs.bam.busy_vnodes | grep -i dns | grep -v "(lin 0)" | awk '{print $4}' | sed -E 's/\)//'`

A valid path for LIN 0x100660007 is /ifs/.ifsvar/modules/flexnet/flx_config.xml


This confirms that the XML configuration file in use by isi_dnsiq_d is flx_config.xml.


OneFS 8.2.1 and later also sees the addition of a ‘-O’ logical overlay flag to ‘isi get’ CLI utility for viewing a file’s compression details. For example:


# isi get –DDO file1

* Size:           167772160

* PhysicalBlocks: 10314

* LogicalSize:    167772160

PROTECTION GROUPS

lbn0: 6+2/2

2,11,589365248:8192[COMPRESSED]#6

0,0,0:8192[COMPRESSED]#10

2,4,691601408:8192[COMPRESSED]#6

0,0,0:8192[COMPRESSED]#10

Metatree logical blocks:

zero=32 shadow=0 ditto=0 prealloc=0 block=0 compressed=64000

 

The logical overlay information is described under the ‘protection groups’ output. This example shows a compressed file where the sixteen-block chunk is compressed down to six physical blocks (#6) and ten sparse blocks (#10). Under the ‘Metatree logical blocks’ section, a breakdown of the block types and their respective quantities in the file is displayed - including a count of compressed blocks.


When compression has occurred, the ‘df’ CLI command will report a reduction in used disk space and an increase in available space. The ‘du’ CLI command will also report less disk space used.

A file that for whatever reason cannot be compressed will be reported as such:

4,6,900382720:8192[INCOMPRESSIBLE]#1

So, to recap, the ‘isi get’ command provides information about an individual or set of file system objects.