On Tue, Dec 22, 2015 at 9:00 AM, Simon Hallam <sha@xxxxxxxxx> wrote: > Thank you both, cleared up a lot. > > Is there a performance metric in perf dump on the MDS' that I can see the active number of inodes/dentries? I'm guessing the mds_mem ino and dn metrics are the relevant ones? > http://paste.fedoraproject.org/303932/77466614/ Those are the number of CInode and CDentry objects allocated, respectively. You can also look at mds -> inodes (there's some subtle difference between mem_mem->ino but I haven't checked what it is -- any of these are probably fine for a rough impression. John > > Cheers, > > Simon > >> -----Original Message----- >> From: Gregory Farnum [mailto:gfarnum@xxxxxxxxxx] >> Sent: 17 December 2015 23:54 >> To: John Spray >> Cc: Simon Hallam; ceph-users@xxxxxxxxxxxxxx >> Subject: Re: Metadata Server (MDS) Hardware Suggestions >> >> On Thu, Dec 17, 2015 at 2:06 PM, John Spray <jspray@xxxxxxxxxx> wrote: >> > On Thu, Dec 17, 2015 at 2:31 PM, Simon Hallam <sha@xxxxxxxxx> wrote: >> >> Hi all, >> >> >> >> >> >> >> >> I’m looking at sizing up some new MDS nodes, but I’m not sure if my >> thought >> >> process is correct or not: >> >> >> >> >> >> >> >> CPU: Limited to a maximum 2 cores. The higher the GHz, the more IOPS >> >> available. So something like a single E5-2637v3 should fulfil this. >> > >> > No idea where you're getting the 2 core part. But a mid range CPU >> > like the one you're looking at is probably perfectly appropriate. As >> > you have probably gathered, the MDS will not make good use of large >> > core counts (though there are plenty of threads and various >> > serialisation/deserialisation parts can happen in parallel). >> >> There's just not much that happens outside of the big MDS lock right >> now, besides journaling and some message handling. So basically two >> cores is all we'll be able to use until that happens. ;) >> >> > >> >> Memory: The more the better, as the metadata can be cached in RAM >> (how much >> >> RAM required is dependent on number of files?). >> > >> > Correct, the more RAM you have, the higher you can set mds_cache_size, >> > and the larger your working set will be. >> >> Note that "working set" there; it's only the active metadata you need >> to worry about when sizing things. I think at last count Zheng was >> seeing ~3KB of memory for each inode/dentry combo. >> -Greg > > > Please visit our new website at www.pml.ac.uk and follow us on Twitter @PlymouthMarine > > Winner of the Environment & Conservation category, the Charity Awards 2014. > > Plymouth Marine Laboratory (PML) is a company limited by guarantee registered in England & Wales, company number 4178503. Registered Charity No. 1091222. Registered Office: Prospect Place, The Hoe, Plymouth PL1 3DH, UK. > > This message is private and confidential. If you have received this message in error, please notify the sender and remove it from your system. You are reminded that e-mail communications are not secure and may contain viruses; PML accepts no liability for any loss or damage which may be caused by viruses. > _______________________________________________ ceph-users mailing list ceph-users@xxxxxxxxxxxxxx http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
 |