On Fri, 11 May 2012 14:55:34 +0000 Daniel Pocock <daniel@xxxxxxxxxxxxx> wrote: > > > While I was adding the SCTERC settings to my rc.local, I had a look over > /sbin/blockdev --setra ... settings > > I do things like this, for example: > > /sbin/blockdev --setra 8192 /dev/mapper/myvg-large_media_files > > What about > - the devices /dev/sd[ab]2 > - the md device, /dev/md2 (which is the PV for LVM) ? > > Would it be correct to leave /dev/sd[ab]2 and /dev/md2 at defaults, and > only specify larger sizes for LVs that need it? Or should I even make > /dev/sd[ab]2 and /dev/md2 smaller than the default value (256)? The read-ahead setting is interpreted by the pagecache. So it only makes sense to set in on a device which is directly mounted or accessed via /dev/XXX. On other devices - such as the media device beneath and md array - you can set the read-ahead to anything or nothing and it will have no effect at all. NeilBrown > > > Those disks are SATA - but I'm also planning to add in some SSDs and > RAID1 them with md - they will hold things like source code and home > directories (to make compiling and NFS home directories faster). Can > anyone comment on the read ahead config or any other aspect of such a plan? > -- > To unsubscribe from this list: send the line "unsubscribe linux-raid" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html
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