Sorry, my "P4" statement came out wrong. What I meant was that one does not need a high-end modern machine for such a server. The workstation we use is dual-processor Dell Precision 470 with ECC RAM. As it happens, we also have an identical computer sitting around in case of a failure. ) I absolutely agree that reliability is paramount.
CPU load-wise:
our software Raid6 with 8 members does not produce CPU loads of >50% when
writing 1 TB. I think 50% of 2x3.2 GHz Prescott-2M CPUs from 2005 is not all
that much, though older single-core processor will struggle in such situation.
Best regards,
Dmitry
On 2013-07-29, at 11:08 AM, Georg Zocher wrote:
> Dear Sergei,
>
> I agree in principle with the setup suggested by Dmitry.
>
> But I would not use an old P4 system to serve as central device for all other
> workstations. Keep in mind that such an old system might have a higher chance
> to fail. As this is your central unit which keeps the work of all other
> members running, I would not trust in such an old machine (beside there is no
> money). Lifetime should be more expensive than hardware...
>
> If you go for such a cheap setup, I would at least configure a second P4
> system, that you can plug-in directly after a hardware failure of system-1.
> Depending on the RAID-level and the number of hard disks, I assume that a P4
> single core will not be sufficient in a setup with several users, especially
> with a software raid setup (although I do not have solid data for it).
>
> I would highly recommend to buy a system which is designed to do a 24/7/365
> job. I installed such a machine in our workgroup three years ago including a
> 3x RAID6 hardware setup for all /home/$USERNAME, diffraction data, and
> crystallographic software. Workstations are attached via 2x1GBit network
> connections (bonding) and are diskless. They get their image from the server
> using tftpboot. This substantially reduces the administration time.
> Especially, it allows you to "setup" a new workstation by simply adding it to
> your dhcp.conf on the server...
>
> All the best,
> Georg
>
>
>
>
>
>
> Am 29.07.2013 15:38, schrieb Dmitry Rodionov:
>> Dear Sergei,
>>
>> IMO, the easiest way to achieve your goals is good old NIS and NFS with a
>> centralized server on wired gigabit network. You could go with LDAP instead
>> of NIS, but it is considerably more difficult to set up.
>> One computer would act as a server, containing the user database, homes and
>> programs.
>> Hardware RAID is not worth it. You are better off getting a Linux-supported
>> SAS/SATA HBA (e.g. Dell SAS 6/iR) and making a software RAID 5 with mdadm
>> out of a bunch of inexpensive consumer-grade SATA disks. You need a minimum
>> of 4 drives for RAID5. An external HDD enclosure might be necessary
>> depending on server's chassis and the desired number of drives.
>> We built our server from an old P4 workstation with a couple gigs of RAM (8
>> clients). Having two or more cores is a benefit.
>> If I am not mistaken, software RAID 5 is not bootable, so you would need an
>> extra drive (can be very small) for the core part of the OS.
>> Export /home and /usr/local with NFS, mount them from client machines, hook
>> the clients up to NIS and you are done. Some programs might not reside in
>> /usr/local in which case you would have to export and mount more directories.
>> Ubuntu community has pretty good and easy to follow guides for NIS, NFS and
>> mdadm.
>>
>> Bets regards,
>> Dmitry
>>
>> On 2013-07-29, at 6:22 AM, Sergei Strelkov wrote:
>>
>>> Dear all,
>>>
>>> In old times I, just like about any protein crystallographer,
>>> used to work on a cluster of SGI/IRIX workstations with complete NFS-based
>>> cross-mounting of hard disks.
>>>
>>> A typical operation included:
>>> 1. A single home directory location for every user:
>>> if my home directory was on workstation X, I would by default use
>>> it after logging on any of the workstations in the cluster.
>>> 2. A single location for all software for general use.
>>> (And, obviously, 3. The ability to log on any node from
>>> any terminal; today this is done via the 'ssh -X' command).
>>>
>>> I wondered if someone could give us an advice on a painless
>>> setup enabling 1. and 2., for a small cluster of Ubuntu computers.
>>> We (will) have about five similar Dell computers in a local (192.168.*.*)
>>> network (wired/wireless). Any tips on the hardware (especially the
>>> LAN and network disks) are also welcome.
>>>
>>> Many thanks,
>>> Sergei
>>>
>>> --
>>> Prof. Sergei V. Strelkov
>>> Laboratory for Biocrystallography
>>> Dept of Pharmaceutical and Pharmacological Sciences, KU Leuven
>>> Herestraat 49 bus 822, 3000 Leuven, Belgium
>>> Work phone: +32 16 330845 Mobile: +32 486 294132
>>> Lab pages: http://pharm.kuleuven.be/anafar
>
>
> --
> Universität Tübingen
> Interfakultäres Institut für Biochemie
> Dr. Georg Zocher
> Hoppe-Seyler-Str. 4
> 72076 Tuebingen
> Germany
> Fon: +49(0)-7071-2973374
> Mail: georg.zoc...@uni-tuebingen.de
> http://www.ifib.uni-tuebingen.de
>
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