Am 17.02.2017 um 02:24 schrieb Anthony Youngman:
On 16/02/17 14:08, Reindl Harald wrote:
Hi
i am new and was redirected to this list from the bugtracker
please have a look at https://bugzilla.kernel.org/show_bug.cgi?id=194551
currently "writemostly" seems to be only supported on "real" RAID1 while
i was in hope that by the conecpt of RAID10 having more or less
RAID0+RAID1 it would also work on RAID10 (and on the virtual machine wre
i tested mdadm with the flag before buying the disks it did not complain)
Be careful. Don't confuse Raid10 with Raid1+0. They are NOT the same
thing (on linux at least), although they are very similar
yeah, i realized that but anyways thought the "writemostly" logic is
there too and maybe the docs not up-to-date
sadly i can't write a patch on my own but only point how useful it would be
let's say you need a fast and really large storage on a mostly-read
workload - take 10x4 TB disks - RAID5/RAID6 is horrible in case of drive
error and rebuild, 10 x 4 TB SSD is horrible in case of pricing
5x4 TB SSD = 5 x 1400 = 7000
5x4 TB HDD = 5 x 100 = 500
total price 7500 versus 14000 for flash-only
surely, you can setup 5 RAID1 and on top RAID0 or LVM for such a large
setup if your start from scratch - on the other hand my current RAID10
is from 2011 where SSD was not such a topic and since the operating
system is RAID10 too the inital setup is not that easy and after
Fedora/RHEL "reworked" anaconda it's more painful to impossible (i even
had enough of the manual partition tool in a virtual machine installing
CentOS7 and created the data partitions after the OS install)
--
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
