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Performance metrics, SolFSdrv & CBFS

Also by EldoS: CallbackDisk
Create virtual disks backed by memory or custom location, expose disk images as disks and more.
#4499
Posted: 12/15/2007 10:41:44
by Jon Anders  (Basic support level)
Joined: 12/15/2007
Posts: 13

We're currently evaluating your products for purchase. During initial testing, we had tentatively concluded that SolFSdrv was best suited to our needs, very pleased with the functionality we experienced. In the past weeks however, during more thorough testing, we've seen some behaviors inconsistent with our initial results. First and foremost, we're seeing substantial performance degradation of SolFSdrv (have not run same test against CBFS) wherein the speed of copying of a large file (ie: > 10GB) into the SolFS container reduces dramatically toward the final 25% or so (as indicated by the Windows progress bar) so that the last portion appears to take multiples of time greater than the first majority. For example, the progress bar may move from zero to 75% within 2 seconds; the balance appears to take almost 10 seconds. We've reviewed other posts here re: performance, but those posts seem to deal with numerous sparse files as opposed to a single large file. Implementing the suggested tweaks (ie: page size config, etc) did seem to resolve that issue for us for sparse files. But we have been unable to resolve this apparent problem with large file (a database table) regardless of tweaks. No compression or encryption is being used. The identical copy outside of the SolFS container results in a smooth transition of the progress bar and completion within approx 3 seconds.

Is our observation valid in your opinion? And, if so, what resolution might you suggest? What types of performance issues can we expect to see with SolFSdrv? Are the tweaks for small, sparse files incompatible with any suggested tweaks to accommodate a large file? Would CBFS behave any differently? While we have thousand of sparse files, we do have a small number of large (>1GB) we'd like to include in the container. Seem to recall reading someplace that theoretically SolFSdrv may be faster than native Windows operations, but what does your experience suggest?

With the container mapped as a network drive, should we expect to see any performance difference? If so, what types of differences? And how might the negative differences be minimized?

#4500
Posted: 12/15/2007 11:13:40
by Eugene Mayevski (EldoS Corp.)

If you create dynamically-sized volumes, then you will have a speed penalty when copying the large files - the volume is resized (growing) and this does take time. The solutions are either to use fixed-sized storage or use SetDiskSize (DiskSize property) to pre-allocate the size in the storage before copying the file.

Also, page size will matter a lot. For large files you need to have large pase size, then allocation of pages takes less time (less allocations needed, less block read/write operations executed etc.). For small (tiny) sparse files large page sizes will lead to overhead in storage. However, if space is not a problem, then you can keep large sizes.

Finally, what version of SolFS did you test? Version 1.5 has its own memory manager designed specifically for SolFS, and so 1.5 is faster than 1.0.

Speed of SolFS Standard edition can be faster than writing many files directly to disk because of smaller number of kernel-mode operations. With Driver edition the situation is not so simple.


Callback File System doesn't store the data so your question is not applicable to it.


Sincerely yours
Eugene Mayevski

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