Watching performance on a DHCP Server
dhcp1 at thehobsons.co.uk
Wed Feb 13 20:04:39 UTC 2008
Frank Bulk wrote:
>How much of a performance advantage would be gained with fsync just by using
>a SCSI or serial ATA flash disk, or a USB thumb drive?
Compared with a single hard drive - a LOT
Compared with a raid controller with caching enabled - not as much
but it depends what else is going on.
If the DHCP writes were the only thing going on, then the raid
controller cache effectively gives you a drive with the same
performance as a ram disk. If the disk system is very busy then it's
not as clear cut as the write may still need to wait for physical
accesses to complete before a place in the cache can be made for it.
However, you would not want to use just any old flash for this, older
flash has a very finite limit to write cycles and can quickly become
useless when storing a busy filesystem. Some newer flash technologies
have eliminated this issue.
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