Date: Tue, 24 Jan 2006 15:53:45 -0600 From: Eric Anderson <anderson@centtech.com> To: Sergey Lungu <sergey.lungu@gmail.com> Cc: freebsd-geom@freebsd.org Subject: Re: GEOM stripe + concat Message-ID: <43D6A1E9.2070207@centtech.com> In-Reply-To: <20060125004419.17dd39b1.sergey.lungu@gmail.com> References: <20060122192257.273734cf.sergey.lungu@gmail.com> <20060124232443.2e252b87.sergey.lungu@gmail.com> <43D6985A.1030101@centtech.com> <20060125004419.17dd39b1.sergey.lungu@gmail.com>
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Sergey Lungu wrote: > On Tue, 24 Jan 2006 15:12:58 -0600 Eric Anderson > <anderson@centtech.com> wrote: > > >> Sergey Lungu wrote: >> >>> On Sun, 22 Jan 2006 19:22:57 +0300 I wrote: >>> >>> >>> >>>> Hello, >>>> >>>> I have FreeBSD 6.0-RELEASE running on my FTP server. There are >>>> three disks on that box: two identical 120GB and one 300GB. I am >>>> using gvinum for stripping between first two disks. I am going to >>>> give gstripe a try, sine gvinum is too unstable. >>>> >>>> >>> Since nobody has answered my question, possibly it was too silly, I >>> decided to experiment a bit. I'll answer my questions: >>> >>> >>> >>>> Am I able to concatenate created stripe with 300GB disk? >>>> >>>> >>> Yes, you can! >>> >>> >>> >>>> And is it wise at all? >>>> >>>> >>> I have made some simple benchmarking on three different geometries. >>> Legend: >>> a * b - stripping between a and b >>> a + b - concatenation of a and b >>> ad1 - 120GB disk >>> ad2 - 120GB disk >>> ad3 - 300GB disk >>> >>> I tried to upload and then download a 700MB movie. Here are my >>> results: >>> >>> ad1 * ad2: >>> Uploading: 1m8.406s >>> Downloading: 1m4.656s >>> >>> ad1 * ad2 + ad3: >>> Uploading: 1m4.115s >>> Downloading: 1m4.962s >>> >>> ad1 + ad2 + ad3: >>> Uploading: 1m4.110s >>> Downloading: 1m4.971s >>> >>> Conclusion: >>> There is no big difference between all this geometries in FTP >>> context, or possibly there are some on high load!? >>> >>> >> I'm not sure the details of your tests, since 'upload and then >> download' doesn't really explain the test, however I'm guessing you >> were limited by network or the destination rather than the local disk >> - 1m 4s looks alot like 100mbit to me. >> > > Yes, we have 100mbit network. > > >> You should try one of the many benchmarking tools as a first start >> (try iozone, or bonnie, etc). >> > > I'm not interested in real disk performance, since this box is used > only for ftp. Probably I was wrong from the begining and I am limited > only by the network speed, so software RAID is not the right way to > boost our ftp server :) > Well, I guess it depends on the files, and the usage. It could be that you are using much less than 100mbit normally, due to the transfer of random small files to many clients. I would guess that if you are not hitting the 100mbit network wall yet, you could benefit from a stripe of multiple disks, and a larger amount of available memory. If all the files you are serving are large (hundreds of megabytes) then you probably won't be disk bound. >> Also, concat won't give you any performance increase, but striping >> could. You could easily test your 700mb file by doing something like >> this: >> >> dd if=/path/to/700mb-file of=/dev/null bs=1m >> > > I don't think that stripping between two disks can give some > significant performance boost (I may be wrong, of course), especially > in ftp context. > Well, stripes can definitely increase disk performance, that's the whole idea. Otherwise, one wouldn't use it, as it increases risk of failure (without the use of a parity drive). > I think I'll use a*b+c geometry, but the question is: Will I have the > same problems with gstripe+gconcat as with gvinum? :) I don't think anyone could answer that without information on what problems you did see with gvinum. Eric -- ------------------------------------------------------------------------ Eric Anderson Sr. Systems Administrator Centaur Technology Anything that works is better than anything that doesn't. ------------------------------------------------------------------------
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