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Operational System for Storage (DomUs)

 

 

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oper.ml at gmail

Apr 14, 2012, 5:32 AM

Post #1 of 5 (352 views)
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Operational System for Storage (DomUs)

Hi guys,

i have a SuperMicro server with an LSI SATA Controler with 16 hdd
attached in RAID50.
I would like to know wich operational system should i work with in
this server? I will have 4 Xen host servers bringing up the DomUs in
iSCSI with a dedicated gigabit network.
I already had experience with the CenOS 5.5, running the TGTD
daemon, e not pleasure one, cause the system keep staying with WAIT
(I/O) reaching 100%, causing the DomUs to hang/freeze and remount the
partitions in RO.
I'm thinking about Ubuntu Server. Does anyone have sugestions and
some experience to share about this?

Thanks alot.
Tony M.


outbackdingo at gmail

Apr 14, 2012, 7:45 PM

Post #2 of 5 (321 views)
Permalink
Re: Operational System for Storage (DomUs) [In reply to]

On Sat, Apr 14, 2012 at 8:32 AM, Oper.ML <oper.ml [at] gmail> wrote:
> Hi guys,
>
>     i have a SuperMicro server with an LSI SATA Controler with 16 hdd
> attached in RAID50.
>     I would like to know wich operational system should i work with in this
> server? I will have 4 Xen host servers bringing up the DomUs in iSCSI with a
> dedicated gigabit network.
>     I already had experience with the CenOS 5.5, running the TGTD daemon, e
> not pleasure one, cause the system keep staying with WAIT (I/O) reaching
> 100%, causing the DomUs
o hang/freeze and remount the partitions in RO.
>     I'm thinking about Ubuntu Server. Does anyone have sugestions and some
> experience to share about this?

Might want to look at FreeNAS, OpenFiler or NexentaStor all open
source and decent
SAN/NAS installs..... my preference is FreeNAS w/ ZFS

>
> Thanks alot.
> Tony M.
>
> _______________________________________________
> Xen-users mailing list
> Xen-users [at] lists
> http://lists.xen.org/xen-users

_______________________________________________
Xen-users mailing list
Xen-users [at] lists
http://lists.xen.org/xen-users


oper.ml at gmail

Apr 16, 2012, 5:20 PM

Post #3 of 5 (323 views)
Permalink
Operational System for Storage (DomUs) [In reply to]

Hi guys,

i have a SuperMicro server with an LSI SATA Controler with 16 hdd
attached in RAID50.
I would like to know wich operational system should i work with in
this server? I will have 4 Xen host servers bringing up the DomUs in
iSCSI with a dedicated gigabit network.
I already had experience with the CenOS 5.5, running the TGTD
daemon, e not pleasure one, cause the system keep staying with WAIT
(I/O) reaching 100%, causing the DomUs to hang/freeze and remount the
partitions in RO.
I'm thinking about Ubuntu Server. Does anyone have sugestions and
some experience to share about this?

Thanks alot.
Tony M.


tobert at gmail

Apr 16, 2012, 6:26 PM

Post #4 of 5 (337 views)
Permalink
Re: Operational System for Storage (DomUs) [In reply to]

On Mon, Apr 16, 2012 at 5:20 PM, Oper.ML <oper.ml [at] gmail> wrote:

> Hi guys,
>
> i have a SuperMicro server with an LSI SATA Controler with 16 hdd
> attached in RAID50.
> I would like to know wich operational system should i work with in
> this server? I will have 4 Xen host servers bringing up the DomUs in iSCSI
> with a dedicated gigabit network.
> I already had experience with the CenOS 5.5, running the TGTD daemon,
> e not pleasure one, cause the system keep staying with WAIT (I/O) reaching
> 100%, causing the DomUs to hang/freeze and remount the partitions in RO.
> I'm thinking about Ubuntu Server. Does anyone have sugestions and some
> experience to share about this?
>

I personally never use iSCSI anymore, but that said, I ran a private cloud
of KVM and Xen instances (65 or so dom0's) at a previous job while also
doing extensive research on silly ways to combine iSCSI volumes into huge
ZFS filesystems. Here is a quick list of stuff to consider:

* consider OpenSolaris ZFS + COMSTAR iSCSI or better yet, NFSv4 (Nexenta,
SmartOS, or OmniOS) for you storage machine, it's awesome
* use the Linux LIO iSCSI target stack! It's vastly superior to just about
all the others under duress
* it was really solid when I tested it a couple years ago (had about
400TB across 20+ systems)
* I also tested ietd, tgtd, COMSTAR, and a few others at that time
* if you can get two switches
* use Linux multipath instead of bonding if you can
* DO NOT bridge the switches (separate VLAN's & subnets)
* this is _really_ critical! You can lose an entire L2 network and keep
on going if you get this right
* Linux distribution is irrelevant, CentOS6 or Ubuntu LTS are both fine
choices though
* I'd go with 12.04 LTS if I was doing this today, build packages as
necessary if LIO isn't there
* use LVM instead of file backed volumes
* file backed volumes pretty much always stink, except under ietd where
it sucks exactly the same amount
* the iSCSI target machine should almost certainly be running the deadline
IO scheduler
* disable Nagle's algorithm
* TCP buffers tuned much larger than the kernel defaults
* kernel is ideally compiled _without_ preemptive mode (most distros ship
this!)
* custom compiled kernels can make a difference in this setting!
* be prepared to install high-quality NIC's if your board didn't ship with
them (all the Supermicro boards I've tested had decent Intel NIC's, but I
was saddled with some Nforce boards at one point which were a disaster)
* enable large frames on the switch and all targets/initiators
* but don't set it to 9000 bytes like everybody does -s ome switches,
especially in the low-mid range screw up 9000 byte packets
* I usually err on the side of caution and page alignment and go with
around 8400 (easily fit 2 pages + headers, being exact doesn't buy you
anything but pain)
* never mix IO and VM traffic if you can help it
* by extension, don't let your IO traffic go over a bridge device
* bonded interfaces are OK if you can't use multipath

Good luck,
-Al


>
> Thanks alot.
> Tony M.
>
>
> _______________________________________________
> Xen-users mailing list
> Xen-users [at] lists
> http://lists.xen.org/xen-users
>


fjwcash at gmail

Apr 16, 2012, 6:32 PM

Post #5 of 5 (319 views)
Permalink
Re: Operational System for Storage (DomUs) [In reply to]

If this box is going to be just an iSCSI target server, then look into
FreeBSD + ZFS (using istgt and ZVols). Or even any of the OpenSolaris forks
+ ZFS (using the new COMSTAR integrated iSCSI support in ZFS). Or, if you
want a support contract, Solaris 11 with ZFS and COMSTOR.

Just because the Xen host boxes run Linux, doesn't mean you have to limit
yourself to Linux on the storage boxes.

Cheers,
Freddie Cash
fjwcash [at] gmail
On Apr 16, 2012 5:24 PM, "Oper.ML" <oper.ml [at] gmail> wrote:

> Hi guys,
>
> i have a SuperMicro server with an LSI SATA Controler with 16 hdd
> attached in RAID50.
> I would like to know wich operational system should i work with in
> this server? I will have 4 Xen host servers bringing up the DomUs in iSCSI
> with a dedicated gigabit network.
> I already had experience with the CenOS 5.5, running the TGTD daemon,
> e not pleasure one, cause the system keep staying with WAIT (I/O) reaching
> 100%, causing the DomUs to hang/freeze and remount the partitions in RO.
> I'm thinking about Ubuntu Server. Does anyone have sugestions and some
> experience to share about this?
>
> Thanks alot.
> Tony M.
>
>
> _______________________________________________
> Xen-users mailing list
> Xen-users [at] lists
> http://lists.xen.org/xen-users
>

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