Messages in this thread | | | Date | Thu, 30 Apr 1998 22:29:28 +0200 (MET DST) | From | Rik van Riel <> | Subject | Re: CDROM jukebox filesystem using autofs |
| |
On Thu, 30 Apr 1998, Dan A. Dickey wrote: > Aaron Passey wrote:
> > So far, I have made it move and mount disks on command and unmount and put away > > disks in an LRU fashion. For example, if I do an ls of /autofs/1, it'll get > > the disk out of slot 1 and put it in one of the drives, mount it and give me > > the ls. > > > > There are several problems I am running into with this approach. First > > of all, what do I do if I have 4 drives, all mounted and busy, and I get a > > request for a fifth disk? > > return EBUSY.
Or you could: - let the user of the first started request wait, and switch drives again after XXX kilobytes (making sure that throughput isn't hurt too much, latency will be bad anyway) - have a caching HD partition and read the biggest file requested for the next X MB, then quickly switch disks to the requested one
> though it was an interesting exercise. Use Occam's (sp?) razor - simple is > better.
For truly high-latency apps this might not be the case. Simply make sure that your readahead (on large files) is big enough (and maybe HD cached) so that no more than 50% of the time/bandwidth is spent switching the disks.
Rik. +-------------------------------------------+--------------------------+ | Linux: - LinuxHQ MM-patches page | Scouting webmaster | | - kswapd ask-him & complain-to guy | Vries cubscout leader | | http://www.phys.uu.nl/~riel/ | <H.H.vanRiel@phys.uu.nl> | +-------------------------------------------+--------------------------+
- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.rutgers.edu
| |