Hello, I 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,
FUA is surely supported by libata.
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...
FUA was introduced by ATA/PI-7. There's no DPO support.
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.
I meant the sector which failed to be written to.
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.
And yet I didn't name the reason of the non-equivalency for DPO: this bit
effectively prohibits drive cache replacement to occur as a result of a
command in question -- this simply has nothing to do with flushing.
Thanks.
/mjt
MBR, Sergei
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