Hello.
Michael Tokarev wrote:
On each and every machine out there, and on every dmesg
output posted on numerous mailinglists, I see messages
similar to this:
scsi 0:0:0:0: Direct-Access ATA ST3250620NS 3.AE PQ: 0 ANSI: 5
SCSI device sda: 488397168 512-byte hdwr sectors (250059 MB)
SCSI device sda: write cache: enabled, read cache: enabled, doesn't support DPO
or FUA
for SATA disk drives. And I wonder -- are those features
supported at all by linux, and/or are there disk drives
out there which supports it as well?
Don't know, the bits have just quite recently been included into ATA spec,
IIRC...
For my Seagate ST3250620NS SATA drive (it's a "server" drive,
whatever it means), I can see -- at least --
* Mandatory FLUSH_CACHE
* FLUSH_CACHE_EXT
reported by hdparm -I. I wonder what "FLUSH CACHE EXT" means,
It reports LBA48 of a failing sector while FLUSH CACHE can only report LBA28.
and whenever it can be used to support DPO and/or FUA...
DPO and FUA bits are a part of SCSI CDB and so only affect the block range
specified by the command in question while FLUSH CACHE [EXT] operates on the
whole cache -- so, it's not equivalent.
Thanks.
/mjt
MBR, Sergei
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