[j-nsp] Flash size requirements [Update on M7]

[Pekka Savola]

On Thu, 22 Jan 2009, michael.firth at bt.com wrote:
> My understanding is that if you have a flash it has to be 1GB or 
> bigger, but if you don't have a flash then it isn't an issue.
>
> The problem is that JunOS is getting bigger, so the 256MB CF cards 
> that used to be used are no longer large enough to hold the root 
> filesystem. With a hard-disk only router, the system just 
> repartitions the hard drive to have less /var space when it needs a 
> bigger root partition.

This is not true.  New releases run just fine with 256 MB flash.
Here's a 'df' output of such a router:

Filesystem  1K-blocks    Used    Avail Capacity  Mounted on
/dev/ad0s1a    222046  129060    75224    63%    /
devfs               1       1        0   100%    /dev
devfs               1       1        0   100%    /dev/
/dev/md0        30300   30300        0   100%    /packages/mnt/jbase
/dev/md1       161002  161002        0   100%    /packages/mnt/jkernel-9.3R2.8
/dev/md2        13624   13624        0   100%    /packages/mnt/jpfe-M40-9.3R2.8
/dev/md3         4552    4552        0   100%    /packages/mnt/jdocs-9.3R2.8
/dev/md4        44830   44830        0   100%    /packages/mnt/jroute-9.3R2.8
/dev/md5        13242   13242        0   100%    /packages/mnt/jcrypto-9.3R2.8
/dev/md6        25984   25984        0   100%    /packages/mnt/jpfe-common-9.3R2.8
/dev/md7      2061286      10  1896374     0%    /tmp
/dev/md8      2061286     984  1895400     0%    /mfs
/dev/ad0s1e     24490      70    22462     0%    /config
procfs              4       4        0   100%    /proc
/dev/ad1s1f  26124907 2955740 21079175    12%    /var

You can see there's plenty of available space on the root filesystem.

One could wonder what could happen at updates, but in jinstalls the 
flash root is reformatted so the free space is not an issue, and with 
jbundles existing files are overwritten (AFAIK), so upgrades should 
not be a problem either.

On 8.5, the root size was as follows:

Filesystem  1K-blocks    Used    Avail Capacity  Mounted on
/dev/ad0s1a    222048  101298   102988    50%    /

The whole flash size debacle is ridiculous in Juniper's release notes. 
When talking about flash size requirements, they keep stating like "at 
least 1GB of memory".  Some PSNs refer to new (real, not flash) memory 
requirements.  I think some folks (technical writers for sure, but 
probably others as well) are seriously confused.

-- 
Pekka Savola                 "You each name yourselves king, yet the
Netcore Oy                    kingdom bleeds."
Systems. Networks. Security. -- George R.R. Martin: A Clash of Kings