Date: Mon, 21 Sep 2015 23:10:15 +0200 From: Ben RUBSON <ben.rubson@gmail.com> To: freebsd-fs@freebsd.org Subject: [HAST] ZFS, many disks, write order Message-ID: <F332F505-F4B3-49D6-8CD7-B53496DCFF3E@gmail.com>
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Hello,
I plan to use HAST to synchronize a ZFS pool between 2 servers.
The ZFS pool has 3 RAID-Z2 VDEVs (8+2), + 3 spares.
+1 mirror for SLOG.
+1 mirror for L2ARC.
So a total of 37 disks (4TB each).
40Gb/s network bandwidth between the 2 servers.
Will I have to define each of the 37 disks/resources in hast.conf ?
Stupid question, but will this setup (with so many resources) work ?
Will write IOs be ordered on the secondary node in the same order (over =
all the 37 devices) as they occurred on the primary node ?
This of course to have the secondary node consistent, even after a power =
failure of the primary during a high IO load, leading into an import -F =
<poolname> on the secondary node.
In HAST, each resource seems to be "independent" from the others.
In DRBD, as an example, we can put several volumes in a same resource to =
guarantee write order over all the volumes (disks) of the resource.
Example :
resource r0 {
volume 0 {
device /dev/drbd0;
disk /dev/c0v0;
}
volume 1 {
device /dev/drbd1;
disk /dev/c0v1;
}
}
What about HAST then ?
Of course I would have liked to have my 37 disks as volumes in the same =
resource, as in the example above.
Thank you very much for your help !
Best regards,
Ben
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