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SubjectRe: default hdparms? readahead=256? Re: WD 400GB xATA Drives
Linda Walsh wrote:
>..
> set to known values may not contain "great values". My "readahead"
> value seems to boot with a value of "256" for all of my drives.
>
> Is this not a bit "excessive"?

Wow.. that does look a bit HUGE. Thanks for pointing it out,
I'm resetting mine back to 128 for now.

> Justin Piszcz wrote:
>> When I write to this disk for a while, I see this in dmesg (only once
>> so far):
>>
>> [31230.223504] ata6: translated ATA stat/err 0x51/04 to SCSI
>> SK/ASC/ASCQ 0xb/00/00
>> [31230.223511] ata6: status=0x51 { DriveReady SeekComplete Error }
>> [31230.223515] ata6: error=0x04 { DriveStatusError }
>>
>> Is there some sort of smart testing going on constantly? I only get
>> 26-27MB/s on this 400GB/SATA/16MB/7200RPM drive. I use smartmontools
>> to do a daily test. However, even with smart disabled, I get:
>>
>> # hdparm -t /dev/sde
>> /dev/sde:
>> Timing buffered disk reads: 78 MB in 3.06 seconds = 25.46 MB/sec
>>
>> Does anyone know if this drive has problems in Linux or something?
>>
>> [ 6.895914] Vendor: ATA Model: WDC WD4000KD-00N Rev: 01.0
...

Some drives suck at sequential reads, in favour of doing random seeks
very very well. Basically, the on-drive seek algorithm may not favour
doing much read-ahead. Try "hdparm -A1" and see if that helps.
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