Hi, Has, or does, anyone use dm-cache - specifically for caching SAN based storage locally? I''m looking for a way to speed up SAN based storage on a CentOS 5.6 + XEN Hypervisor which uses iSCSI mounted SAN storage. dm-cache seems like it do the trick, but I''ve never heard of it before until someone mentioned it in another mailing list. A quick search on google didn''t really give me much in terms of actual user experience. Does anyone use it? Any feedback? Pitfalls? Success stories? -- Kind Regards Rudi Ahlers SoftDux Website: http://www.SoftDux.com Technical Blog: http://Blog.SoftDux.com Office: 087 805 9573 Cell: 082 554 7532 _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
Hi, 2011/6/24 Rudi Ahlers <Rudi@softdux.com>:> I''m looking for a way to speed up SAN based storage on a CentOS 5.6 + XEN > Hypervisor which uses iSCSI mounted SAN storage. dm-cache seems like it doI think the "write-through-write-around" (wt) version of flashcache[*] might be better for the SSD caching use case. I haven''t tried it but you just basically made me stumble over it and it seems the right thing for a Xen host. There''s also documentation on using it with Centos5.4 - good enough? :) A write-back cache is also possible (and there''s more work ongoing to add something like that to linux) but I think a busy VM host will eat through a SSD in too short time if we''re caching writes. I want to use that on my hosts since they only have 8 disks slots (so 6 normal 10k/15k disks on raid controller & 1 ssd & tbd).With a "real" SAN I''d just trust in a reasonable number of raid10 spindles though - SAN storage should be faster, not slower than local disks :>> Does anyone use it? > Any feedback? Pitfalls? Success stories?As to actual _use_ i noted XCP 1.0 has "local storage caching" but there is no documentation what makes up that feature. [*] https://github.com/facebook/flashcache Regards, Florian -- the purpose of libvirt is to provide an abstraction layer hiding all xen features added since 2006 until they were finally understood and copied by the kvm devs. _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users