Fwd: Re: ssd for zfs

[Steven Hartland]

You could add a DA_Q_NO_SYNC_CACHE quirk for you device
which will prevent the cam layer attempting to call sync but this
will only work if its attached to a SCSI controller like an LSI there's
no such quirk currently implemented in ATA cam layer.

    Regards
    Steve
----- Original Message ----- 
From: <krichy at cflinux.hu>
To: <freebsd-scsi at freebsd.org>
Sent: Friday, November 29, 2013 8:17 PM
Subject: Re: Fwd: Re: ssd for zfs


> Dear scsi-devs,
> 
> It seems that my device handles the flush commands slowly. The linux 
> code avoids issuing this if the device reports its write cache is turned 
> off. That way my SSD works fast under linux, but infortunately slow 
> under FreeBSD. Actually I dont understand why is it slow for the flush 
> command, as it has power-loss-protection, maybe for such a command it 
> really flushes everything out, dont know. But when I enable the write 
> cache in linux also, the block layer gets knowledge of the write cache, 
> it issues the flush commands, and it gets same slow.
> 
> How could this be solved?


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