- Joined
- 24 Jan 2002
- Messages
- 12,388
this is cute...got it reading a post from Jaimie Hanrahan;
first, the common method of looking at the percent a disk is fragmented really doesn't tell you anything about how often the files you access are affected by the fragmentation
for instance, if 75 percent of your drive is fragmented, but those files are hardly ever accessed, then all that really matters is the 25% of the disc that you access all the time...if these aren't fragmented, there's not going to be any gain what so ever with a defrag.
if you're on a server that you need to have "up" as much as possible, you can ignore the percentage of fragmentation and just look to the actual affect the fragmentation is having on your work load
this method is more accurate
open perfmon, (windows key+r, type "perfmon" hit enter)
on one of the counters at the bottom right click, hit add counters.
on the pull down, go to "physical disc". (logical disc might be better)
in the window, add "split IO/sec"
then in the same window add "disc transfer"
Split IO/Sec reports the rate which I/Os to the disk were split into more then one I/O.
this happens for one of two reasons...one is rare..a request for data that's too big to fit into a single I/O or the more common reason, that the data for the IO is fragmented.
Disk Transfers/sec is the rate of the read and write operations on the disk.(total IO's)
if split IO's is about 10% or more of the total, there's probably a performance hit...the file team might suggest 20% to 50% before a user would notice a difference.
obviously, you might want to defrag just for the sake of doing it, but this is kinda cute just for the knowledge of it.
first, the common method of looking at the percent a disk is fragmented really doesn't tell you anything about how often the files you access are affected by the fragmentation
for instance, if 75 percent of your drive is fragmented, but those files are hardly ever accessed, then all that really matters is the 25% of the disc that you access all the time...if these aren't fragmented, there's not going to be any gain what so ever with a defrag.
if you're on a server that you need to have "up" as much as possible, you can ignore the percentage of fragmentation and just look to the actual affect the fragmentation is having on your work load
this method is more accurate
open perfmon, (windows key+r, type "perfmon" hit enter)
on one of the counters at the bottom right click, hit add counters.
on the pull down, go to "physical disc". (logical disc might be better)
in the window, add "split IO/sec"
then in the same window add "disc transfer"
Split IO/Sec reports the rate which I/Os to the disk were split into more then one I/O.
this happens for one of two reasons...one is rare..a request for data that's too big to fit into a single I/O or the more common reason, that the data for the IO is fragmented.
Disk Transfers/sec is the rate of the read and write operations on the disk.(total IO's)
if split IO's is about 10% or more of the total, there's probably a performance hit...the file team might suggest 20% to 50% before a user would notice a difference.
obviously, you might want to defrag just for the sake of doing it, but this is kinda cute just for the knowledge of it.
