Hi Don, Did you configure target_ dirty_ratio, target_full_ratio and target_max_bytes?
K.Mohamed Pakkeer On Thu, Apr 30, 2015 at 10:26 PM, Don Doerner <don.doer...@quantum.com> wrote: > All, > > > > Synopsis: I can’t get cache tiering to work in HAMMER on RHEL7. > > > > Process: > > 1. Fresh install of HAMMER on RHEL7 went well. > > 2. Crush map adapted to provide two “root” level resources > > a. “ctstorage”, to use as a cache tier based on very > high-performance, high IOPS SSD (intrinsic journal). 2 OSDs. > > b. “ecstorage”, to use as an erasure-coded poolbased on > low-performance, cost effective storage (extrinsic journal). 12 OSDs. > > 3. Established a pool “ctpool”, 32 PGs on ctstorage (pool size = > min_size = 1). Ran a quick RADOS bench test, all worked as expected. Cleaned > up. > > 4. Established a pool “ecpool”, 256 PGs on ecstorage (5+3 profile). Ran > a quick RADOS bench test, all worked as expected. Cleaned up. > > 5. Ensured that both pools were empty (i.e., “rados ls” shows no > objects) > > 6. Put the cache tier on the erasure coded storage (one Bloom hit > set, interval 900 seconds), set up the overlay. Used defaults for > flushing and eviction. No errors. > > 7. Started a 3600-second write test to ecpool. > > > > Objects piled up in ctpool (as expected) – went past the 40% mark (as > expected), then past the 80% mark (unexpected), then ran into the wall (95% > full – *very* unexpected). Using “rados df”, I can see that the cache > tier is full (duh!) but not one single object lives in the ecpool. Nothing > was ever flushed, nothing was ever evicted. Thought I might be > misreading that, so I went back to SAR data that I captured during the > test: the SSDs were the only [ceph] devices that sustained I/O. > > > > I based this experiment on another (much more successful) experiment that > I performed using GIANT (.1) on RHEL7 a couple of weeks ago (wherein I used > RAM as a cache tier); that all worked. It seems there are at least three > possibilities… > > · I forgot a critical step this time around. > > · The steps needed for a cache tier in HAMMER are different than > the steps needed in GIANT (and different than the documentation online). > > · There is a problem with HAMMER in the area of cache tier. > > > > Has anyone successfully deployed cache-tiering in HAMMER? Did you have > to do anything unusual? Do you see any steps that I missed? > > > > Regards, > > > > -don- > > > ------------------------------ > The information contained in this transmission may be confidential. Any > disclosure, copying, or further distribution of confidential information is > not permitted unless such privilege is explicitly granted in writing by > Quantum. Quantum reserves the right to have electronic communications, > including email and attachments, sent across its networks filtered through > anti virus and spam software programs and retain such messages in order to > comply with applicable data security and retention requirements. Quantum is > not responsible for the proper and complete transmission of the substance > of this communication or for any delay in its receipt. > > _______________________________________________ > ceph-users mailing list > ceph-users@lists.ceph.com > http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com > > -- Thanks & Regards K.Mohamed Pakkeer Mobile- 0091-8754410114
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