On 4/6/2011 7:50 AM, Lori Alt wrote:
On 04/ 6/11 07:59 AM, Arjun YK wrote:
Hi,
I am trying to use ZFS for boot, and kind of confused about how the
boot paritions like /var to be layed out.
With old UFS, we create /var as sepearate filesystem to avoid various
logs filling up the / filesystem
I believe that creating /var as a separate file system was a common
practice, but not a universal one. It really depended on the
environment and local requirements.
With ZFS, during the OS install it gives the option to "Put /var on a
separate dataset", but no option is given to set quota. May be,
others set quota manually.
Having a separate /var dataset gives you the option of setting a quota
on it later. That's why we provided the option. It was a way of
enabling administrators to get the same effect as having a separate
/var slice did with ufs. Administrators can choose to use it or not,
depending on local requirements.
So, I am trying to understand what's the best practice for /var in
ZFS. Is that exactly same as in UFS or is there anything different ?
I'm not sure there's a defined "best practice". Maybe someone else
can answer that question. My guess is that in environments where,
before, a separate ufs /var slice was used, a separate zfs /var
dataset with a quota might now be appropriate.
Lori
Could someone share some thoughts ?
Thanks
Arjun
Traditionally, the reason for a separate /var was one of two major items:
(a) /var was writable, and / wasn't - this was typical of diskless or
minimal local-disk configurations. Modern packaging systems are making
this kind of configuration increasingly difficult.
(b) /var held a substantial amount of data, which needed to be handled
separately from / - mail and news servers are a classic example
For typical machines nowdays, with large root disks, there is very
little chance of /var suddenly exploding and filling / (the classic
example of being screwed... <wink>). Outside of the above two cases,
about the only other place I can see that having /var separate is a good
idea is for certain test machines, where you expect frequent memory
dumps (in /var/crash) - if you have a large amount of RAM, you'll need a
lot of disk space, so it might be good to limit /var in this case by
making it a separate dataset.
--
Erik Trimble
Java System Support
Mailstop: usca22-123
Phone: x17195
Santa Clara, CA
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