JP Vossen on 25 Mar 2008 15:38:04 -0700 |
> Date: Wed, 19 Mar 2008 22:45:08 -0400 > From: brent timothy saner <brent.saner@gmail.com> > Subject: Re: [PLUG] Using 'noatime' in fstab? > > JP Vossen wrote: >> I read someplace that you can reduce wear and tear on hard drives >> by including noatime in the mount options. I already do this for >> the one system I have using a CF card, but I was wondering about it >> just in general. >> >> I have several servers that rsync themselves various places for >> backups. That means that every time I rsync the entire filesystem, >> a gazillion atimes are being updated for essentially no reason. >> Ditto for the s/locate indexer. I can't recall ever using an atime >> for anything (ctime and mtime yes, atime no). >> >> Can anyone give me a good reason not to do this on some/all of my >> machines? All of my machines are ext3, some have H/W EIDE RAID, >> others have software (MDM) mirroring, some are just plain old hard >> drives, if it matters. Most are Debian or Ubuntu but I have a >> couple of CentOS4 boxes too. And what about for machines in a VM? > > it is in my general opinion that for most contexts, atime is > absolutely useless. i'd venture that it really doesn't offer much a > benefit (and yes, it DOES do more wear-and-tear). It recently occurred to me tmpreaper does use atime, though it has options for using m or ctime as well. The stock Debian Etch tmpreaper.conf uses atime AFAICT. Since my /tmp is on a different partition, I've just left atime alone on that one. > two things, though. > > 1. please please PLEASE don't use ext3 with CF, use ext2 or fat (and > please don't use fat. it's useless). all that journaling can > potentially kill your storage if you're using CF. Errr, that's a good point I'd not considered. In my case it doesn't matter much, as the CF-card isn't written to very often. All syslog goes elsewhere, and swap, /tmp and /data are on a hard disk. Since it's a pain to get console access, I'm going to leave ext3 to less the chances of getting stuck at fsck after ungraceful shutdowns. (It has a UPS, but...) FAT? Yuck. I'd use ext2 if it mattered. I use FAT32 on some USB drives that need to be portable, but otherwise... :-) > 2. another really smart idea is to mount /var/log, /var/tmp, and /tmp > (and more as you see fit) as ramdisks. you can do this by adding the > following to fstab: I disagree there. The FHS specifies that /var/tmp contents must be persistent across reboots [1]. And being a Security Geek I definitely don't agree with throwing logs away (I just send everything to a logserver). /tmp would be OK though. At any rate, in this particular case I'm much more RAM constrained than disk constrained. / and the OS are on CF, but there is 500G hard disk for data and other, including /tmp. I don't think I moved /var/tmp, but very little happens on the machine that needs that. (Just checked, the only thing in /var/tmp is a vi.recover from 2005 and the only thing in /tmp is SSH sessions. :) Of possible interest is that the CF card contains a fairly minimal Debian Etch (just upgraded from Sarge), plus OpenSSH, Postfix, Samba, NFS, Apache2, Bind9, gcc, NTP, SVN, DHCP3, and BackupPC in 469M. 81M of that is /usr/share which could go away, and there are other places I could trim, but it not worth the time since the CF is 1G. Later, JP _______________ [1] http://www.pathname.com/fhs/pub/fhs-2.3.pdf, page 38: 5.15. /var/tmp : Temporary files preserved between system reboots 5.15.1. Purpose The /var/tmp directory is made available for programs that require temporary files or directories that are preserved between system reboots. Therefore, data stored in /var/tmp is more persistent than data in /tmp. Files and directories located in /var/tmp must not be deleted when the system is booted. Although data stored in /var/tmp is typically deleted in a site-specific manner, it is recommended that deletions occur at a less frequent interval than /tmp. ----------------------------|:::======|------------------------------- JP Vossen, CISSP |:::======| jp{at}jpsdomain{dot}org My Account, My Opinions |=========| http://www.jpsdomain.org/ ----------------------------|=========|------------------------------- "Microsoft Tax" = the additional hardware & yearly fees for the add-on software required to protect Windows from its own poorly designed and implemented self, while the overhead incidentally flattens Moore's Law. ___________________________________________________________________________ Philadelphia Linux Users Group -- http://www.phillylinux.org Announcements - http://lists.phillylinux.org/mailman/listinfo/plug-announce General Discussion -- http://lists.phillylinux.org/mailman/listinfo/plug
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