[zfs-discuss] windows on thin provision zvol: how to force trim?

Ivan Krutskikh stein.hak at gmail.com
Tue Oct 15 08:45:05 EDT 2013


Basically, I wanted to use zvols for windows diskless booting. Maybe ntfs
compression would be a nice choice. I'll think about it, thanks!


2013/10/15 Gordan Bobic <gordan.bobic at gmail.com>

> That's what I use on my VMs. You might also find it is better to use
> compression on the client end than on the ZFS side. That way your ZFS
> storage box doesn't take the CPU hit for all of the compression going
> to/from the FS, plus you get less bandwidth saturation on your interconnect
> between the storage and the VM. For my Windows VMs I use NTFS compression
> and ZLE on the ZFS side. Just make sure that the disk scrubbing sdelete
> performs isn't subject to ntfs compression or you might find that for the
> purpose of the scrub your storage suddenly becomes infinite. :)
>
>
> On Tue, Oct 15, 2013 at 1:33 PM, Ivan Krutskikh <stein.hak at gmail.com>wrote:
>
>> Okay, one promissing solution is to use sdelete from microsoft ( original
>> post http://nex7.blogspot.ru/2013/03/zvol-used-space.html), which would
>> zero-out all unused space on a zvol. However, this seams write-intensive.
>> I'll test this solution and report the results
>>
>>
>> 2013/10/15 Gordan Bobic <gordan.bobic at gmail.com>
>>
>>> So don't overbook. If your pool gets to 100% full you are going to have
>>> major performance issues due to fragmentation anyway. Filling it up from
>>> 95% to 100% is likely to be so slow it'll give you ample time (days) to go
>>> and delete some snapshots or similar to free up some space.
>>>
>>>
>>> On Tue, Oct 15, 2013 at 1:12 PM, Ivan Krutskikh <stein.hak at gmail.com>wrote:
>>>
>>>> My concern is resilvering time for a server full of zvol's and clones
>>>>
>>>> I already use lz4, but once the zvol goes full 100%- It does not shink
>>>> back to original, even if the data is already deleted from the filesystem
>>>>
>>>>
>>>> 2013/10/15 Gordan Bobic <gordan.bobic at gmail.com>
>>>>
>>>>> I don't think they are expected to shrink. Even if the trim gets
>>>>> passed to the underlying media I'm not sure if the container's size is also
>>>>> expected to shrink.
>>>>>
>>>>> If you are concerned about space usage, enable ZLE compression and run
>>>>> a cron job that zeroes out the free space inside the VMs. Or better, don't
>>>>> overbook the space.
>>>>>
>>>>>
>>>>> On Tue, Oct 15, 2013 at 12:22 PM, Ivan Krutskikh <stein.hak at gmail.com>wrote:
>>>>>
>>>>>> Okay, I've googled up to DisableDeleteNotify parameter. If it equals
>>>>>> 0 (which it is by default in fact), then TRIM should be up and running. But
>>>>>> my zvol devices do not shring with deletion of files from virtual machines
>>>>>> disks. How come?
>>>>>>
>>>>>>
>>>>>> 2013/10/15 Tamas Papp <tompos at martos.bme.hu>
>>>>>>
>>>>>>>
>>>>>>> On 10/15/2013 11:20 AM, Ivan Krutskikh wrote:
>>>>>>> > http://comments.gmane.org/gmane.os.solaris.opensolaris.zfs/35630
>>>>>>> >
>>>>>>> > Please, look through the original post
>>>>>>> >
>>>>>>>
>>>>>>> Ohh, thanks.
>>>>>>>
>>>>>>> tamas
>>>>>>>
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