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@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 Iôve seen the impact myself, and I definitely > donôt > 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@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 ++++++++++++++++++++++++++++++++++++++++