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Re: [libvirt] [PATCHv3] qemu: reduce file padding requirements



On 06/10/2010 03:31 PM, Eric Blake wrote:
Followup to https://bugzilla.redhat.com/show_bug.cgi?id=599091,
commit 20206a4b, to reduce disk waste in padding.

* src/qemu/qemu_monitor.h (QEMU_MONITOR_MIGRATE_TO_FILE_BS): Drop
back to 512.
(QEMU_MONITOR_MIGRATE_TO_FILE_TRANSFER_SIZE): New macro.
* src/qemu/qemu_driver.c (qemudDomainSaveFlag): Update comment.
* src/qemu/qemu_monitor_text.c (qemuMonitorTextMigrateToFile): Use
two invocations of dd to output non-aligned large blocks.
* src/qemu/qemu_monitor_json.c (qemuMonitorJSONMigrateToFile):
Likewise.
---

v2: avoid truncating regular file destination

v3: change minimum block size from 512 to 4k, to avoid unaligned
RMW cycles on newer disks with 4k sectors

Okay, I've finally gotten around to trying this out, and in addition to reducing the file size, it also works!

ACK

(Note: I haven't tested saving to a block device, so I'm taking the word of the dd documentation that this works as well ;-)


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