> On Oct 2, 2024, at 2:19 PM, quag...@bol.com.br wrote:
> 
> Hi Kyriazis,
>      I work with a cluster similar to yours : 142 HDDs and 18 SSDs.
>      I had a lot of performance gains when I made the following settings:
> 
> 1-) For the pool that is configured on the HDDs (here, home directories are 
> on HDDs), reduce the following replica settings (I don't know what your 
> resilience requirement is):
> *size=2
> * min_size=1
> 
>       I do this for at least 4 years with no problems (even when there is a 
> need to change discs or reboot a server, this config never got me in trouble).
> 
It is nonetheless risky.  The wrong sequence of cascading events, of 
overlapping failures and you may lose data.  


> 2-) Move the filesystem metadata pools to use at least SSD only.
> 
Absolutely.  The CephFS docs suggest using size=4 for the MD pool.


> 
> 3-) Increase server and client cache.
> Here I left it like this:
> osd_memory_target_autotune=true (each OSD always has more than 12G).
> 
> For clients:
> client_cache_size=163840                                                      
>                                  
> client_oc_max_dirty=1048576000                                                
>                                    
> client_oc_max_dirty_age=50
> client_oc_max_objects=10000                                                   
>                                      
> client_oc_size=2097152000                                                     
>                               
> client_oc_target_dirty=838860800
> 
>      Evaluate, following the documentation, which of these variables makes 
> sense for your cluster.
> 
>      For the backup scenario, I imagine that decreasing the size and min_size 
> values will change the impact. However, you must evaluate your needs for 
> these settings.
> 
> 
> Rafael.
> 
>  
> 
> De: "Kyriazis, George" <george.kyria...@intel.com>
> Enviada: 2024/10/02 13:06:09
> Para: ebl...@nde.ag, ceph-users@ceph.io
> Assunto: [ceph-users] Re: Question about speeding hdd based cluster
>  
> Thank you all.
> 
> The cluster is used mostly for backup of large files currently, but we are 
> hoping to use it for home directories (compiles, etc.) soon. Most usage would 
> be for large files, though.
> 
> What I've observed with its current usage is that ceph rebalances, and 
> proxmox-initiated VM backups bring the storage to its knees.
> 
> Would a safe approach be to move the metadata pool to ssd first, see how it 
> goes (since it would be cheaper), and then add DB/WAL disks? How would ceph 
> behave if we are adding DB/WAL disks "slowly" (ie one node at a time)? We 
> have about 100 OSDs (mix hdd/ssd) spread across about 25 hosts. Hosts are 
> server-grade with plenty of memory and processing power.
> 
> Thank you!
> 
> George
> 
> 
> > -----Original Message-----
> > From: Eugen Block <ebl...@nde.ag>
> > Sent: Wednesday, October 2, 2024 2:18 AM
> > To: ceph-users@ceph.io
> > Subject: [ceph-users] Re: Question about speeding hdd based cluster
> >
> > Hi George,
> >
> > the docs [0] strongly recommend to have dedicated SSD or NVMe OSDs for
> > the metadata pool. You'll also benefit from dedicated DB/WAL devices.
> > But as Joachim already stated, it depends on a couple of factors like the
> > number of clients, the load they produce, file sizes etc. There's no easy 
> > answer.
> >
> > Regards,
> > Eugen
> >
> > [0] https://docs.ceph.com/en/latest/cephfs/createfs/#creating-pools
> >
> > Zitat von Joachim Kraftmayer <joachim.kraftma...@clyso.com>:
> >
> > > Hi Kyriazis,
> > >
> > > depends on the workload.
> > > I would recommend to add ssd/nvme DB/WAL to each osd.
> > >
> > >
> > >
> > > Joachim Kraftmayer
> > >
> > > www.clyso.com <http://www.clyso.com/>
> > >
> > > Hohenzollernstr. 27, 80801 Munich
> > >
> > > Utting a. A. | HR: Augsburg | HRB: 25866 | USt. ID-Nr.: DE2754306
> > >
> > > Kyriazis, George <george.kyria...@intel.com> schrieb am Mi., 2. Okt.
> > > 2024,
> > > 07:37:
> > >
> > >> Hello ceph-users,
> > >>
> > >> I’ve been wondering…. I have a proxmox hdd-based cephfs pool with no
> > >> DB/WAL drives. I also have ssd drives in this setup used for other pools.
> > >>
> > >> What would increase the speed of the hdd-based cephfs more, and in
> > >> what usage scenarios:
> > >>
> > >> 1. Adding ssd/nvme DB/WAL drives for each node 2. Moving the metadata
> > >> pool for my cephfs to ssd 3. Increasing the performance of the
> > >> network. I currently have 10gbe links.
> > >>
> > >> It doesn’t look like the network is currently saturated, so I’m
> > >> thinking
> > >> (3) is not a solution. However, if I choose any of the other
> > >> options, would I need to also upgrade the network so that the network
> > >> does not become a bottleneck?
> > >>
> > >> Thank you!
> > >>
> > >> George
> > >>
> > >> _______________________________________________
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