On Fri, September 8, 2017 12:56 pm, hw wrote: > Valeri Galtsev wrote: >> >> On Fri, September 8, 2017 9:48 am, hw wrote: >>> m.roth at 5-cent.us wrote: >>>> hw wrote: >>>>> Mark Haney wrote: >>>> <snip> >>>>>> BTRFS isn't going to impact I/O any more significantly than, say, >>>>>> XFS. >>>>> >>>>> But mdadm does, the impact is severe. I know there are ppl saying >>>>> otherwise, but I´ve seen the impact myself, and I definitely >>>>> don´t >>>>> want >>>>> it on that particular server because it would likely interfere with >>>>> other services. >>>> <snip> >>>> I haven't really been following this thread, but if your requirements >>>> are >>>> that heavy, you're past the point that you need to spring some money >>>> and >>>> buy hardware RAID cards, like LSI, er, Avago, I mean, who's bought >>>> them >>>> more recently? >>> >>> Heavy requirements are not required for the impact of md-RAID to be >>> noticeable. >>> >>> Hardware RAID is already in place, but the SSDs are "extra" and, as I >>> said, >>> not suited to be used with hardware RAID. >> >> Could someone, please, elaborate on the statement that "SSDs are not >> suitable for hardware RAID". > > When you search for it, you´ll find that besides wearing out undesirably > fast --- which apparently can be contributed mostly to less overcommitment > of the drive --- you may also experience degraded performance over time > which can be worse than you would get with spinning disks, or at least not > much better. Thanks. That seems to clear fog a little bit. I still would like to hear manufacturers/models here. My choices would be: Areca or LSI (bought out by Intel, so former LSI chipset and microcode/firmware) and as SSD Samsung Evo SATA III. Does anyone who used these in hardware RAID can offer any bad experience description? I am kind of shying away from "crap" hardware which in a long run is more expensive, even though looks cheaper (Pricegrabber is your enemy - I would normally say to my users). So, I never would consider using poorly/cheaply designed hardware in some setup (e.g. hardware RAID based storage) one expects performance from. Am I still taking chance hitting "bad" hardware RAID + SSD combination? Just curious where we actually stand. Thanks again for fruitful discussion! Valeri > > Add to that the firmware being designed for an entirely different > application > and having bugs, and your experiences with surprisingly incompatible > hardware, > and you can imagine that using an SSD not designed for hardware RAID > applications with hardware RAID is a bad idea. There is a difference like > night and day between "consumer hardware" and hardware you can actually > use, > and that is not only the price you pay for it. > _______________________________________________ > CentOS mailing list > CentOS at centos.org > https://lists.centos.org/mailman/listinfo/centos > ++++++++++++++++++++++++++++++++++++++++ Valeri Galtsev Sr System Administrator Department of Astronomy and Astrophysics Kavli Institute for Cosmological Physics University of Chicago Phone: 773-702-4247 ++++++++++++++++++++++++++++++++++++++++