On Tue, 20 Jan 2015, Daniel Pocock wrote: > On 20/01/15 14:25, Benjamin Coddington wrote: > > Hi Daniel, > > > > On Mon, 19 Jan 2015, Daniel Pocock wrote: > >> I've been looking into the issue of which storage controllers are > >> suitable for use with NFS + BtrFs (or NFS + ZFS) and put some comments > >> about it on my blog[1] today. > >> > >> I understand that for NFS it is generally desirable to have non-volatile > >> write cache if you want good write performance. > >> > >> On the other hand, self-healing file systems (BtrFs and ZFS) like having > >> direct access to disks and those RAID cards with caches don't always > >> give the same level of access to the volume. > >> > >> Can anybody give any practical suggestions about how to reconcile these > >> requirements and experience good NFS write performance onto these > >> filesystems given the type of HBA and RAID cards available? > > I don't think that reconciling these requirements is going to necessarily > > equal good NFS write performance. You've got to define what good means. > > It sounds like you want fast commits, but how fast, how many, what size? > More specific example of the use-case will probably answer that: > - consider a home network or small office, less than 10 users > - aim to improve the performance of tasks such as: > - unzipping source tarballs with many files in them > - switching between branches in Git when many files change > - compiling large projects with many object files or Java class files > to be written > and/or building packages > > For compiling, I can obviously generate my object files on tmpfs or some > other workaround to get performance. It looks like you have reproduceable workload - that's going to make your testing much easier. > > If you're building on ZFS, best thing would be to find a very fast ZIL > > device, but if you're already building pools on SSD to get any gain you'd > > need something really fast like DDR. A ramdrive ZIL might be a nice way to > > test that on your setup before spending anything. > > > > Many BBU-d RAID controllers allow JBOD modes that still slice up their > > cache for writes to disk, for example check out megacli's > > "-CfgEachDskRaid0". > > Thanks for that feedback > > I had been using BtrFs and md at present (1TB for each) and I'm thinking > about going up to 4TB or 6TB and deciding whether to use BtrFs or ZFS on > most of it. If you make discoveries, let me know what you find out. Ben -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
