Thomas> I'm planning on setting up a dual raid5 array for hosting vm's Thomas> off LVM, I would like to add an ssd cache to help with typical Thomas> server system loads, and some mixed read/write loads for game Thomas> servers. Thomas> I'm wondering what the "best" route for me to go is. There's a Thomas> few options that I know of, like flashcache, dm-cache, and Thomas> bcache. The question is which of those is better suited to my Thomas> use case? I looked into both bcache and lvmcache and went with lvmcache because it made more sense to me. But one restriction is that the cache LVs must be in the same VGs as the volume to cache. So you might need to partition your SSD(s) and put the partitions into seperate VGs so that you can cache one or more LVs. I'm using it at home to cache a RAID1 4tb VG, with a pair of mirrored SSDs. I'm a big believer in mirroring, esp for critical stuff like this. Unfortunately, I don't have a good performance measurements of how much help this actually gives me. It *feels* faster, but since I don't have before/after measurements, I could just have wasted a bunch of money. So I'd recommend lvmcache overall, since it does seem to help, but push for better performance metrics and measurement. Heh, maybe it's time for me to start writing up lvmcachetop to help measure things. John -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
