Understanding ‘Total inlined data savings’ When Using ’isi_cstats’
Thu, 12 May 2022 14:22:45 -0000|
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Recently a customer contacted us to tell us that he thought that there was an error in the output of the OneFS CLI command ‘isi_cstats’. Starting with OneFS 9.3, the ‘isi_cstats’ command includes the accounted number of inlined files within /ifs. It also contains a statistic called “Total inlined data savings”.
This customer expected that the ‘Total inlined data savings’ number was simply ‘Total inlined files’ multiplied by 8KB. The reason he thought this number was wrong was that this number does not consider the protection level.
In OneFS, for the 2d:1n protection level, each file smaller than 128KB is stored as 3X mirrors. Take the screenshot below as an example.
If we do some calculation here,
379,948,336 * 8KB = 3,039,586,688KiB = 2898.78GiB
we can see that the 2,899GiB from the command output is calculated as one block per inlined file. So, in our example, the customer would think that ‘Total inlined data savings’ should report 2898.78 GiB * 3, because of the 2d:1n protection level.
Well, this statistic is not the actual savings, it is really the logical on-disk cost for all inlined files. We can't accurately report the physical savings because it depends on the non-inlined protection overhead, which can vary. For example:
- If the protection level is 2d:1n, without the data inlining in 8KB inode feature, each of the inlined files would cost 8KB * 3.
- If the protection level is 3d:1n1d, it will become 8KB * 4.
One more thing to consider, if a file is smaller than 8KB after compression, it will be inlined into an inode as well. Therefore, this statistic doesn't represent logical savings either, because it doesn't take compression into account. To report the logical savings, total logical size for all inlined files should be tracked.
To avoid any confusion, we plan to rename this statistic to “Total inline data” in the next version of OneFS. We also plan to show more useful information about total logical data of inlined files, in addition to “Total inline data”.
For more information about the reporting of data reduction features, see the white paper PowerScale OneFS: Data Reduction and Storage Efficiency on the Info Hub.
Author: Yunlong Zhang, Principal Engineering Technologist
Related Blog Posts
OneFS Data Reduction and Efficiency Reporting
Wed, 04 May 2022 14:36:26 -0000|
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Among the objectives of OneFS reduction and efficiency reporting is to provide ‘industry standard’ statistics, allowing easier comprehension of cluster efficiency. It’s an ongoing process, and prior to OneFS 9.2 there was limited tracking of certain filesystem statistics – particularly application physical and filesystem logical – which meant that data reduction and storage efficiency ratios had to be estimated. This is no longer the case, and OneFS 9.2 and later provides accurate data reduction and efficiency metrics at a per-file, quota, and cluster-wide granularity.
The following table provides descriptions for the various OneFS reporting metrics, while also attempting to rationalize their naming conventions with other general industry terminology:
Also Known As
Data size including sparse data, zero block eliminated data, and CloudPools data stubbed to a cloud tier.
Data size excluding protection overhead and sparse data, and including data efficiency savings (compression and deduplication).
Capacity savings from zero removal.
Capacity savings from deduplication.
Capacity savings from in-line compression.
Data size excluding protection overhead and including storage efficiency savings.
Size of erasure coding used to protect data.
Total footprint of data including protection overhead FEC erasure coding) and excluding data efficiency savings (compression and deduplication).
Deduplication ratio. Will be displayed as 1.0:1 if there are no deduplicated blocks on the cluster.
Usable reduction ratio from compression, calculated by dividing ‘logical data’ by ‘preprotected physical’ and expressed as x:1.
Inlined data ratio
Efficiency ratio from storing small files’ data within their inodes, thereby not requiring any data or protection blocks for their storage.
Data reduction ratio
Effective to Usable
Usable efficiency ratio from compression and deduplication. Will display the same value as the compression ratio if there is no deduplication on the cluster.
Effective to Raw
Overall raw efficiency ratio expressed as x:1
So let’s take these metrics and look at what they represent and how they’re calculated.
- Application logical, or protected logical, is the application data that can be written to the cluster, irrespective of where it’s stored.
- Removing the sparse data from application logical results in filesystem logical, also known simply as logical data or effective. This can be data that was always sparse, was zero block eliminated, or data that has been tiered off-cluster by means of CloudPools, and so on.
(Note that filesystem logical was not accurately tracked in releases prior to OneFS 9.2, so metrics prior to this were somewhat estimated.)
- Next, data reduction techniques such as compression and deduplication further reduce filesystem logical to application physical, or pre-protected physical. This is the physical size of the application data residing on the filesystem drives, and does not include metadata, protection overhead, or data moved to the cloud.
- Filesystem physical is application physical with data protection overhead added – including inode, mirroring, and FEC blocks. Filesystem physical is also referred to as protected physical.
- The data reduction ratio is the amount that’s been reduced from the filesystem logical down to the application physical.
- Finally, the storage efficiency ratio is the filesystem logical divided by the filesystem physical.
With the enhanced data reduction reporting in OneFS 9.2 and later, the actual statistics themselves are largely the same, just calculated more accurately.
The storage efficiency data was available in releases prior to OneFS 9.2, albeit somewhat estimated, but the data reduction metrics were introduced with OneFS 9.2.
The following tools are available to query these reduction and efficiency metrics at file, quota, and cluster-wide granularity:
OneFS Platform API
isi get -D
isi quota list -v
isi statistics data-reduction
Note that the ‘isi_cstats’ CLI command provides some additional, behind-the-scenes details. The interface goes through platform API to fetch these stats.
The ‘isi statistics data-reduction’ CLI command is the most comprehensive of the data reduction reporting CLI utilities. For example:
# isi statistics data-reduction Recent Writes Cluster Data Reduction (5 mins) --------------------- ------------- ---------------------- Logical data 6.18M 6.02T Zero-removal saved 0 - Deduplication saved 56.00k 3.65T Compression saved 4.16M 1.96G Preprotected physical 1.96M 2.37T Protection overhead 5.86M 910.76G Protected physical 7.82M 3.40T Zero removal ratio 1.00 : 1 - Deduplication ratio 1.01 : 1 2.54 : 1 Compression ratio 3.12 : 1 1.02 : 1 Data reduction ratio 3.15 : 1 2.54 : 1 Inlined data ratio 1.04 : 1 1.00 : 1 Efficiency ratio 0.79 : 1 1.77 : 1
The ‘recent writes’ data in the first column provides precise statistics for the five-minute period prior to running the command. By contrast, the ‘cluster data reduction’ metrics in the second column are slightly less real-time but reflect the overall data and efficiencies across the cluster. Be aware that, in OneFS 9.1 and earlier, the right-hand column metrics are designated by the ‘Est’ prefix, denoting an estimated value. However, in OneFS 9.2 and later, the ‘logical data’ and ‘preprotected physical’ metrics are tracked and reported accurately, rather than estimated.
The ratio data in each column is calculated from the values above it. For instance, to calculate the data reduction ratio, the ‘logical data’ (effective) is divided by the ‘preprotected physical’ (usable) value. From the output above, this would be:
6.02 / 2.37 = 1.76 Or a Data Reduction ratio of 2.54:1
Similarly, the ‘efficiency ratio’ is calculated by dividing the ‘logical data’ (effective) by the ‘protected physical’ (raw) value. From the output above, this yields:
6.02 / 3.40 = 0.97 Or an Efficiency ratio of 1.77:1
OneFS SmartQuotas reports the capacity saving from in-line data reduction as a storage efficiency ratio. SmartQuotas reports efficiency as a ratio across the desired data set as specified in the quota path field. The efficiency ratio is for the full quota directory and its contents, including any overhead, and reflects the net efficiency of compression and deduplication. On a cluster with licensed and configured SmartQuotas, this efficiency ratio can be easily viewed from the WebUI by navigating to File System > SmartQuotas > Quotas and Usage. In OneFS 9.2 and later, in addition to the storage efficiency ratio, the data reduction ratio is also displayed.
Similarly, the same data can be accessed from the OneFS command line by using the ‘isi quota quotas list’ CLI command. For example:
# isi quota quotas list Type AppliesTo Path Snap Hard Soft Adv Used Reduction Efficiency ---------------------------------------------------------------------------- directory DEFAULT /ifs No - - - 6.02T 2.54 : 1 1.77 : 1 ----------------------------------------------------------------------------
More detail, including both the physical (raw) and logical (effective) data capacities, is also available by using the ‘isi quota quotas view <path> <type>’ CLI command. For example:
# isi quota quotas view /ifs directory Path: /ifs Type: directory Snapshots: No Enforced: No Container: No Linked: No Usage Files: 5759676 Physical(With Overhead): 6.93T FSPhysical(Deduplicated): 3.41T FSLogical(W/O Overhead): 6.02T AppLogical(ApparentSize): 6.01T ShadowLogical: - PhysicalData: 2.01T Protection: 781.34G Reduction(Logical/Data): 2.54 : 1 Efficiency(Logical/Physical): 1.77 : 1
To configure SmartQuotas for in-line data efficiency reporting, create a directory quota at the top-level file system directory of interest, for example /ifs. Creating and configuring a directory quota is a simple procedure and can be performed from the WebUI by navigating to File System > SmartQuotas > Quotas and Usage and selecting Create a Quota. In the Create a quota dialog, set the Quota type to ‘Directory quota’, add the preferred top-level path to report on, select ’Application logical size’ for Quota Accounting, and set the Quota Limits to ‘Track storage without specifying a storage limit’. Finally, click the ‘Create Quota’ button to confirm the configuration and activate the new directory quota.
The efficiency ratio is a single, current-in time efficiency metric that is calculated per quota directory and includes the sum of in-line compression, zero block removal, in-line dedupe, and SmartDedupe. This is in contrast to a history of stats over time, as reported in the ‘isi statistics data-reduction’ CLI command output, described above. As such, the efficiency ratio for the entire quota directory will reflect what is actually there.
Author: Nick Trimbee
Disabling the WebUI and other Non-essential Services
Mon, 25 Jul 2022 13:43:38 -0000|
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In today's security environment, organizations must adhere to governance security requirements, including disabling specific HTTP services.
OneFS release 184.108.40.206 has introduced an option to disable non-essential cluster services selectively rather than disabling all HTTP services. Disabling selectively allows administrators to determine which services are necessary. Disabling the services allows other essential services on the cluster to continue to run. You can disable the following non-essential services:
- PowerScaleUI (WebUI)
- Rest Access to Namespace (RAN)
Each of these services can be disabled independently and has no impact on other HTTP-based data services. The services can be disabled through the CLI or API with the ISI_PRIV_HTTP privilege. To manage the non-essential services from the CLI, use the isi http services list command to list the services. Use the isi http services view and isi http services modify commands to view and modify the services. The impact of disabling each of the services is listed in the following table.
HTTP services impacts
The WebUI is entirely disabled. Attempting to access the WebUI displays Service Unavailable. Please contact Administrator.
Disabling the Platform-API-External service does not impact the Platform-API-Internal service of the cluster. The Platform-API-Internal services continue to function, even if the Platform-API-External service is disabled. However, if the Platform-API-External service is disabled, the WebUI is also disabled at that time, because the WebUI uses the Platform-API-External service.
RAN (Remote Access to Namespace)
If RAN is disabled, use of the Remote File Browser UI component is restricted in the Remote File Browser and the File System Explorer.
If RemoteService is disabled, the remote support UI and the InProduct Activation UI components are restricted.
To disable the WebUI, use the following command:
isi http services modify --service-id=PowerScaleUI --enabled=false
Author: Aqib Kazi