Re: Does WD driver support MaxMultSect=16, and is it safe for a mysql server?
On 29.09.06 11:10, bbb wrote:
> Subject: Does WD driver support MaxMultSect=16, and is it safe for a mysql server?
> My WD driver `hdparm -i` shows thatt it support multiple sector I/O
> and MaxMultSect=16. But the hdparm manual shows that the value can not
> be set too large especially for WD driver, or it will corrupt the file
> system.
>
> Does your drivers set the hdparm -m16 to speed up driver r/w
> operations, especially when your driver is WD. Because I am running a
> mysql service, and database r/w ability is very important.
afaik multsect is only suported when DMA is not in use. DMA speeds up
transfers much mode, so you should focus on it.
> Some drives, however (most notably the WD Caviar series), seem to run
> slower with multiple mode enabled. Your mileage may vary. Most drives
> support the minimum settings of 2, 4, 8, or 16 (sectors). Larger settings
> may also be possible, depending on the drive. A setting of 16 or 32 seems
> optimal on many systems. Western Dig- ital recommends lower settings of 4
> to 8 on many of their drives, due tiny (32kB) drive buffers and
> non-optimized buffer- ing algorithms. The -i flag can be used to find the
> maximum setting supported by an installed drive (look for MaxMultSect in
> the output). Some drives claim to support multiple mode, but lose data at
> some settings. Under rare circumstances, such failures can result in
> massive filesystem corruption.
this is very old comment, (>5 years IIRC), and I'm not sure if it applies to
newer drives.
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