02-25-2019
Quote:
I am in the market looking to purchase a new E950 server and I am trying to decide between using local SSD drives or SSD based SAN. The application that will be running on this server is read-intensive so I am looking for the most optimal configuration to support this application. There are no other servers or applications that will use this SAN (if I decide to go that route.) The deciding factor to me is Performance regardless of the hardware cost (granted I don't want to pay for something I end up not using.) SAN or local SSD (both running RAID 10)? This is really the question I am trying to answer before I pull the trigger and complete this purchase. Any insights from this community is greatly appreciated.
There are a few more points to consider IMHO:
1) disks (regardless which technology) will over time malfunction and need to be replaced. There is some effort involved in such a replacement. SAN systems have usually ways to - more or less - "effortless" replacing disks built in because they usually are used to deal with a lot of disks and the chance that one disk malfunctions rises with the number of disks involved. You might want to do some risk calculation based on how often on average you expect a disk to break (there is usually a "MTBF" - "meantime between failure" number available), how long you expect the change to take and how much a downtime of the expected duration will cost.
2) SANs and local disks do differ in the way they are attached to the system. Local disks may use SCSI or the "M.2" interface. Notice that you cannot have several local (SSD-) disks attached via M.2. SAN, onthe other hand, may use a FC-connection or even several FC-connections in parallel (FC-drivers allow this for redundancy as well as load-balancing). The capacity of such FC-connections may by far exceed the speed of local disks. On the other hand you will need not only a SAN but also a FC-switch (Brocade are the most wide-spread) and the administration ("zoning") will be more complicated.
3) SANs - if set up with this in mind - may add redundancy and thus high-availability to the system. Again, it depends on the system, its purpose, etc.. to calculate properly the risk of it failing for some amount of time. Calculate how much it would set you back to have the system offline for: 1 hour / 1day / 1 week and this will give you an idea how much money spent on preventing these kinds of desasters is worthwhile.
4) SAN systems for themselves are rather expensive. To alleviate this they become cheaper and cheaper (in comparison to local disks) the more you virtualise and the more systems use it. So, a plan to buy a SAN system for a single system only might be on the expensive side but with a expectation of adding other systems using it too the costs may still be reasonable. So you may want to rethink your immediate problem in a more gobal context.
5) Notice that for a system optimised for speed you need an adequate backup solution. For this you also need a disaster scenario plan to estimate what the costs could be and hence how much the prevention may cost. Then you know how fast a recovery needs to be and therefore which technologies you need to employ to get that speed. You can use a SAN also for snapshots (perhaps quickest way of recovering a "point in time"), very fast medium to put an online backup to, only then migrating it to slower media like tapes and similar solutions. You might want to take that also into consideration.
I hope this helps.
bakunin
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LEARN ABOUT DEBIAN
rsockd
RSOCKD(8) System Manager's Manual RSOCKD(8)
NAME
rsockd - SOCKSified SOCKS server
SYNOPSIS
rsockd [ -ver | -i | -I ]
DESCRIPTION
rsockd is the SOCKSified version of the SOCKS server sockd. Functionally rsockd is identical to sockd except that it may (though not nec-
essarily has to) make use of other SOCKS servers to reach some destinations. A number of rsockd's can be strung together or organized in a
cascade or other more complicated structures to serve the needs of a particular network configuration and restrictions. Obviously this
complicates the issues and make the setup and maintenance of the firewall more difficult. So use sockd instead whenever you can.
This document only describes the features of rsockd that are different from sockd. You should read sockd(5) carefully to gain a basic
understanding of of how the SOCKS server works.
When rsockd receives a request, it checks the request again its configuration (in exactly the same way that sockd does) to decider whether
the request is to be accepted. The primary difference between sockd and rsockd is in how they establish connection to the destination host
of a accepted request. sockd assumes that it can connect directly to the destination host and proceeds to do so. rsockd makes no such
assumption. Instead, it consults another configuration file to decide whether it can connect directly to the particular destination host or
whether it has to use a proxy connection through another SOCKS server. In other words, it behaves just like a versatile SOCKS client in
this regard. Therefore rsockd requires not only the SOCKS server configuration file /etc/sockd.fc or /etc/sockd.conf to decide whether to
accept or reject a request, but also the client configuration file /etc/socks.fc or /etc/socks.conf to decide how to reach the destination
host. If it is a multi-homed version and supports RBIND, it also needs the route file /etc/sockd.fr or /etc/sockd.fr to decide which net-
work interface to use for a connection.
Look at it in a different way, you can think of sockd as a special case of rsockd, one which can connect directly to all destination hosts.
In fact, an rsockd using the client configuration consisting of only this line
direct ALL 0.0.0.0
is functinally identical to the regular sockd.
Anther thing to mention is related to the use of identd. Only the SOCKS server which the requesting host directly connects to can find out
the identity of the real user. Suppose user x on host C connects to rsockd on server B which in turn connects to sockd on server A in order
to reach destination z. Host B can query identd on host C to find out whether the user is indeed x. To host A, the request appears to orig-
inate from user x on host B. An identd query from Host A to host B returns the userid that owns the rsockd process on host B, not the real
user x.
OPTIONS
See sockd(8).
EXAMPLES
The follwoing is an example of the client configuration file. See related man pages for examples on server configuration and route files.
# /etc/socks.conf for rsockd of domain rnd.xyz.com
#
# Use proxy connection through SOCKS server on socks.market.xyz.com
# to reach hosts within market.xyz.com
sockd @=socks.market.xyz.com .market.xyz.com 0.0.0.0
#
# Use direct connect to all other hosts within xyz.com
direct .xyz.com 0.0.0.0
#
# Use proxy connection through SOCKS server on gateway.xyz.com
# to reach all others
sockd @=gateway.xyz.com ALL 0.0.0.0
FILES
/etc/sockd.fc, /etc/sockd.conf, /etc/sockd.fr, /etc/sockd.route, /etc/socks.fc, /etc/socks.conf, /etc/inetd.conf, /etc/services,
/var/adm/messages, /etc/syslog.conf
SEE ALSO
sockd(8), socks_clients(1), sockd.conf(5), sockd.route(5), socks.conf(5), make_sockdfc(8), make_sockdfr(8), dump_sockdfc(8),
dump_sockdfr(8)
AUTHOR
Ying-Da Lee, ylee@syl.dl.nec.com
May 6, 1996 RSOCKD(8)