Am Wednesday 10 April 2013 23:54:28 schrieb Stan Hoeppner: > On 4/10/2013 12:32 PM, Dexter Filmore wrote: > > Am Wednesday 10 April 2013 18:05:08 schrieb Ross Boylan: > >>> You cannot get more than about 200MB/s out of a RAID1 setup, not even > >>> with > >>> 15krpm SAS drives. the RAID1 will never be faster than a single disk. > >>> How > >>> would it. > >> > >> It can read faster than a single disk by combining reads from different > >> sectors on different disks. I think your assertion is incorrect for > >> reading, though not for writing. > >> > >> Ross Boylan > > > > Then dm would have to manage/combine the reads from the involved disks. > > I do not know better, but I doubt this is done. > > I'll ask the raid list for curiousity's sake. > > It's not necessary to ask on linux-raid, and as you have not yet done > so, I'll clarify this now: > > Both the md RAID1 and RAID10 personalities will read sectors in parallel > from both disks in a mirror pair in most circumstances. This has been > the case for many years. This is a read optimization only. Writes > occur in parallel as well, obviously, but as it's the same data the net > data throughput isn't doubled, only the raw device throughput. This > should be obvious to anyone. I'm merely being complete in my description. > > -- > Stan Interesting. Only 1 and 10 or 5/6 as well? -- -----BEGIN GEEK CODE BLOCK----- Version: 3.12 GCS d--(+)@ s-:+ a C++++ UL++ P+>++ L+++>++++ E-- W++ N o? K- w--(---) !O M+ V- PS+ PE Y++ PGP t++(---)@ 5 X+(++) R+(++) tv--(+)@ b++(+++) DI+++ D- G++ e* h>++ r* y? ------END GEEK CODE BLOCK------
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