Hi all, I was just playing a little bit with bcache and it works fine. But if I try random IOPS writes (writeback) on a file larger than the cache, it seems not to work? At least I get a performance as without bcache.
I used a RAID-6 of 8 SSDs (each 238 GiB) as a cache and a RAID-6 of 10 HDDs (2794 Gib). For my test I did random writes of 4k blocks. With 8 threads writing on one 1000 GB file, I get IOPS in the range of 20000, but with a file of 10000 GB I end up with about 400 IOPS. That is the same as without cache. Did I miss something? Is caching disabled in such cases? I would expect, that even in this case (writeback and random writes) it should work as well. Even after a few minutes I get these results, so it is not a problem of a full cache. Has anyone a hint for me, what is going wrong? Best regards Dirk -- +----------------------------------------------------------------------+ | Dr. Dirk Geschke / Plankensteinweg 61 / 85435 Erding | | Telefon: 08122-559448 / Mobil: 0176-96906350 / Fax: 08122-9818106 | | [email protected] / [email protected] / [email protected] | +----------------------------------------------------------------------+ -- To unsubscribe from this list: send the line "unsubscribe linux-bcache" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
