Note: This bug is displayed in read-only format because the product is no longer active in Red Hat Bugzilla.
This project is now read‑only. Starting Monday, February 2, please use https://ibm-ceph.atlassian.net/ for all bug tracking management.

Bug 1509359

Summary: [RHCS 2.y] Change default of rocksdb to no compression
Product: [Red Hat Storage] Red Hat Ceph Storage Reporter: Mike Hackett <mhackett>
Component: RADOSAssignee: Josh Durgin <jdurgin>
Status: CLOSED ERRATA QA Contact: Parikshith <pbyregow>
Severity: medium Docs Contact: Aron Gunn <agunn>
Priority: medium    
Version: 2.4CC: agunn, anharris, ceph-eng-bugs, dzafman, gfarnum, hnallurv, jdurgin, kchai, kdreyer, vumrao
Target Milestone: rc   
Target Release: 2.5   
Hardware: Unspecified   
OS: Unspecified   
Whiteboard:
Fixed In Version: RHEL: ceph-10.2.10-1.el7cp Ubuntu: ceph_10.2.10-2redhat1xenial Doc Type: Enhancement
Doc Text:
.Changing the default compression behavior of `rocksdb` Disabling compression reduces the size of the I/O operations, but not the I/O operations themselves. The old default values: ---- filestore_rocksdb_options = "max_background_compactions=8;compaction_readahead_size=2097152" ---- The new default values: ---- filestore_rocksdb_options = "max_background_compactions=8;compaction_readahead_size=2097152;compression=kNoCompression" ---- Also, this does not effect any existing OSD, only those OSDs that have been manually converted or newly provisioned OSDs.
 Story Points: ---
Clone Of: Environment:
Last Closed: 2018-02-21 19:44:55 UTC Type: Bug
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:
Bug Depends On:    
Bug Blocks: 1536401    

Description Mike Hackett 2017-11-03 15:40:44 UTC 
Description of problem:
Disable compression by default on rocksdb.

Current Default:

filestore_rocksdb_options = "max_background_compactions=8;compaction_readahead_size=2097152"

Recommended change for default disabling compression:

filestore_rocksdb_options = "max_background_compactions=8;compaction_readahead_size=2097152;compression=kNoCompression"
Comment 3 Greg Farnum 2017-11-03 16:09:24 UTC 
I do not believe disabling compression is an appropriate default. While it can help in some situations, compression reduces the amount of disk IO OSDs must perform. Especially at this late date in the 2.x series it seems inappropriate to change such a consequential value on our users.
Comment 5 Sage Weil 2017-11-03 16:28:23 UTC 
It reduces the *size* of the IOs, but not the IOs themselves.  The SST files just end up being larger instead of smaller, but they contain the same keys.

Note that this is changing the *rocksdb* compression default, and rocksdb support is brand new--this won't effect any existing OSD, only those that run the latest downstream and either manually convert leveldb->rocksdb with ceph-kvstore-tool or set filestore_omap_backend=rocksdb and provision a new osd.
Comment 19 errata-xmlrpc 2018-02-21 19:44:55 UTC 
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory, and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://access.redhat.com/errata/RHBA-2018:0340