--- kishor bhagwat <aaaaarrrgghhh(a)yahoo.com> wrote:
--- Nilesh Chaudhari <listbox(a)nilesh.net>
Animesh Singh wrote:
> There should be little to no data loss in
zero data loss = 'synchronous' solution.
anything other than this is async - where ur data
unpredictable - can be zero to any number of I/Os.
> What will be the best way to have Disaster
> Recovery of site ( File & Print and Messaging
> remote location with approx. 300 km. distance.
> & with 2Mbps link.
one 2 Mbps IP link can transfer 2 x 0.8 x 1000 / 8 =
Kilobytes of data per second.(0.8 becoz 20% of IP
That means your data at primary should have a change
much less than this if you want synchronous
But is it fesible to have Site1 synchronous
replication with Site2, Site2 synchronous replication
with Site3 and Site3 ynchronous replication with Site1
There can never be `no data loss'. Some data
lost in such incidents
where a whole site goes down.
Not true. You can have zero data loss solutions -
is...they need humungous bandwidth and/or they screw
your application response times.
Very true, Veritas GCM, does same, with IP Bandwidth.
This is no specific distance limitation that serves as
the delimiter between synchronous & asynchronous modes
of operation as it is really a dependency of network
architecture ( i.e. SAN, switches, that can support
the distance & subjective tolerance to the introduced
latency.) A general rule of thumb that is sometimes
deployed in enterprises is a latency time of less then
500 milliseconds, round trip.
You have these options
for Linux/*nix -
1. journalling file system
2. tar, gunzip
3. dd, cp
5. taper, cdrw-taper
6. linux single
9. and so on...
none of these will work. you need to use proprietary
solutions that will intercept Write calls to the OS,
transfer them to DR site, actually write to remote
get an acknowledge from there, write to local disk,
*only then* acknowledge a successful write to
applcation.(now u know why zero data loss solutions
bomb and screw up app response times)
What will be the impact of BIC TCP over 2Mbps link.
They claim, "BIC can reportedly achieve speeds roughly
6,000 times that of DSL and 150,000 times that of
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