On Fri, Dec 21, 2012 at 5:42 AM, Helmut Jarausch <[email protected]> wrote: > Hi, > > I'd like to put some subdirectory trees (of / and of /usr and of /home) onto > an SSD. > For that I'd like to count the disk accesses which go to a given > subdirectory tree > in some given time intervall. > > Is there any utility which can measure this? > > Many thanks for a hint, > Helmut. >
Hi Helmut, Only responding to say I'd been looking for something to do the same thing myself and haven't found anything. That said, a couple of points: 1) You should be able to watch for issues using smartctl, assuming a modern SSDs. 2) In a post where I asked about this sort of stuff in the Vertex forums I received the following response from folks who seem to have more experience than I. Of course, take this with a grain of salt: [QUOTE] Just using round numbers and assuming effective wear leveling, your 30 GB file may get rewritten once a month. That's 25% of the 128 GB drive, so each NAND cell will get rewritten 3 times a year. If the NAND is good for 10,000 rewrites, you have LOTS of years available... Even if it's rewritten every day, that's 100 NAND rewrites/year, or 100 years of NAND life based on rewrites. You can use any numbers you want, but it will still likely come out to "longer than we care about"... [/QUOTE] Keep in mind that the idea of 'effective wear leveling' is ___really___ important here. Unlike an HD, SSDs do not write over and over to the same location forever. If a block of the drive starts to get heavily used, in terms of number of writes, then firmware will move the block to another location and remap the address. This happens in the drive, not by the OS, so it's invisible to us. (First order anyway - there are probably ways to find out but I'm not looking for those.) Anyway, as there hadn't been any responses I thought I would... Cheers, Mark
