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Re: [Qemu-devel] iSCSI support for QEMU
From: |
Christoph Hellwig |
Subject: |
Re: [Qemu-devel] iSCSI support for QEMU |
Date: |
Thu, 21 Apr 2011 11:09:35 +0200 |
User-agent: |
Mutt/1.5.17 (2007-11-01) |
> In my patch, there are NO data integrity issues.
> Data is sent out on the wire immediately as the guest issues the write.
> Once the guest issues a flush call, the flush call will not terminate
> until the SYNCCACHE10 task has completed.
No guest will even issue a cache flush, as we claim to be WCE=0 by default.
Now if you target has WCE=1 it will cache data internally, and your
iscsi initiator will never flush it out to disk.
We only claim WCE=1 to the guest if cache=writeback or cache=none are
set. So ignoring the issue of having a cache on the initiator side
you must implement stable writes for the default cache=writethrough
behaviour by either seeting the FUA bit on your writes, or doing
a cache flush after every write in case the target does not support FUA.
- [Qemu-devel] iSCSI support for QEMU, Ronnie Sahlberg, 2011/04/21
- [Qemu-devel] [PATCH] iSCSI block driver support, Ronnie Sahlberg, 2011/04/21
- Re: [Qemu-devel] iSCSI support for QEMU, Christoph Hellwig, 2011/04/21
- Re: [Qemu-devel] iSCSI support for QEMU, ronnie sahlberg, 2011/04/21
- Re: [Qemu-devel] iSCSI support for QEMU,
Christoph Hellwig <=
- Re: [Qemu-devel] iSCSI support for QEMU, ronnie sahlberg, 2011/04/21
- Re: [Qemu-devel] iSCSI support for QEMU, Stefan Hajnoczi, 2011/04/21
- Re: [Qemu-devel] iSCSI support for QEMU, ronnie sahlberg, 2011/04/21
- Re: [Qemu-devel] iSCSI support for QEMU, Stefan Hajnoczi, 2011/04/21
- Re: [Qemu-devel] iSCSI support for QEMU, ronnie sahlberg, 2011/04/21
- Re: [Qemu-devel] iSCSI support for QEMU, Kevin Wolf, 2011/04/21
- Re: [Qemu-devel] iSCSI support for QEMU, Stefan Hajnoczi, 2011/04/21
- Re: [Qemu-devel] iSCSI support for QEMU, Christoph Hellwig, 2011/04/21
- Re: [Qemu-devel] iSCSI support for QEMU, ronnie sahlberg, 2011/04/21
- Re: [Qemu-devel] iSCSI support for QEMU, ronnie sahlberg, 2011/04/21