10:10 a.m.
What is the best practice for iSCSI storage domains:
Many small targets vs a few large targets?
Specific example: if you wanted a 8TB storage domain would you prepare a
single 8TB LUN or (for example) 8 x 1 TB LUNs.
--
Richard Chan
1:51 p.m.
On Thu, Dec 7, 2017 at 9:10 AM, Richard Chan <richard(a)treeboxsolutions.com>
wrote:
What is the best practice for iSCSI storage domains:
Many small targets vs a few large targets?
Specific example: if you wanted a 8TB storage domain would you prepare a
single 8TB LUN or (for example) 8 x 1 TB LUNs.
There could be many reasons to use each type.
From the top of my head I think that configuration wise it will be
better
to configure more than one lun.
That can be helpful if you plan to use external LUN disks for example.
Multiple targets might also come useful if you plan to configure iSCSI
multipath in the future, that way you can choose only part of the targets
to apply the MPIO on.
--
Richard Chan
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3:38 p.m.
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That's one of the reasons I prefer File storage (like NFS) than iSCSI or
Fiberchannel. A lot more flexible and manageable.
In the past for VMFS5 I used to work with 4TB LUNs. Now a days something
between 4TB and 8TB may be ok given the bigger size of VMs, depending on
your enviroment of course. However one thing to take attention in this
scenario is how the metadata update process and how that can impact
performance on bigger LUNs.
Fernando
On 07/12/2017 08:51, Maor Lipchuk wrote:
On Thu, Dec 7, 2017 at 9:10 AM, Richard Chan
<richard(a)treeboxsolutions.com <mailto:richard@treeboxsolutions.com>>
wrote:
What is the best practice for iSCSI storage domains:
Many small targets vs a few large targets?
Specific example: if you wanted a 8TB storage domain would you
prepare a single 8TB LUN or (for example) 8 x 1 TB LUNs.
There could be many reasons to use each type.
From the top of my head I think that configuration wise it will be
better to configure more than one lun.
That can be helpful if you plan to use external LUN disks for example.
Multiple targets might also come useful if you plan to configure iSCSI
multipath in the future, that way you can choose only part of the
targets to apply the MPIO on.
--
Richard Chan
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<p>That's one of the reasons I prefer File storage (like NFS) than
iSCSI or Fiberchannel. A lot more flexible and manageable.</p>
<p>In the past for VMFS5 I used to work with 4TB LUNs. Now a days
something between 4TB and 8TB may be ok given the bigger size of
VMs, depending on your enviroment of course. However one thing to
take attention in this scenario is how the metadata update process
and how that can impact performance on bigger LUNs.</p>
<p>Fernando<br>
</p>
<br>
<div class="moz-cite-prefix">On 07/12/2017 08:51, Maor Lipchuk
wrote:<br>
</div>
<blockquote type="cite"
cite="mid:CAJ1JNOeoPC0nOsHY3Tsym7nLCr5-o7fQUKsChUWGYDiEeMZf7w@mail.gmail.com">
<div dir="ltr">
<div class="gmail_extra">
<div class="gmail_quote">On Thu, Dec 7, 2017 at 9:10 AM,
Richard Chan <span dir="ltr"><<a
href="mailto:richard@treeboxsolutions.com"
target="_blank"
moz-do-not-send="true">richard(a)treeboxsolutions.com</a>&gt;</span>
wrote:<br>
<blockquote class="gmail_quote" style="margin:0px 0px 0px
0.8ex;border-left:1px solid
rgb(204,204,204);padding-left:1ex">
<div dir="ltr">
<div>
<div>What is the best practice for iSCSI storage
domains:<br>
<br>
</div>
Many small targets vs a few large targets?</div>
<div><br>
</div>
<div>Specific example: if you wanted a 8TB storage
domain would you prepare a single 8TB LUN or (for
example) 8 x 1 TB LUNs.</div>
</div>
</blockquote>
<div><br>
</div>
<div>There could be many reasons to use each type.</div>
<div>From the top of my head I think that configuration wise
it will be better to configure more than one lun.</div>
<div>That can be helpful if you plan to use external LUN
disks for example.
<div><br>
</div>
</div>
<div>Multiple targets might also come useful if you plan to
configure iSCSI multipath in the future, that way you can
choose only part of the targets to apply the MPIO on.</div>
<div> </div>
<blockquote class="gmail_quote" style="margin:0px 0px 0px
0.8ex;border-left:1px solid
rgb(204,204,204);padding-left:1ex">
<div dir="ltr">
<div><span class="gmail-HOEnZb"><font
color="#888888"><br>
</font></span></div>
<span class="gmail-HOEnZb"><font
color="#888888">
<div>
<div>
<div>
<div>
<div><br>
</div>
<div><br clear="all">
<br>
-- <br>
<div
class="gmail-m_-4508890179059665979gmail_signature">
<div dir="ltr">
<div>
<div dir="ltr">
<div dir="ltr"><font
color="#000000" face="Droid
Sans"><span
style="font-size:15px">Richard
Chan</span></font></div>
<br>
</div>
</div>
</div>
</div>
</div>
</div>
</div>
</div>
</div>
</font></span></div>
<br>
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<br>
</blockquote>
</div>
<br>
<br>
</div>
</div>
<br>
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3:54 p.m.
On Thu, Dec 7, 2017 at 12:51 PM, Maor Lipchuk <mlipchuk(a)redhat.com> wrote:
On Thu, Dec 7, 2017 at 9:10 AM, Richard Chan
<richard(a)treeboxsolutions.com
> wrote:
> What is the best practice for iSCSI storage domains:
>
> Many small targets vs a few large targets?
>
> Specific example: if you wanted a 8TB storage domain would you prepare a
> single 8TB LUN or (for example) 8 x 1 TB LUNs.
>
There could be many reasons to use each type.
From the top of my head I think that configuration wise it will be better
to configure more than one lun.
That can be helpful if you plan to use external LUN disks for example.
Multiple targets might also come useful if you plan to configure iSCSI
multipath in the future, that way you can choose only part of the targets
to apply the MPIO on.
That only makes configuration more complex.
I think for 8TB, a single LUN should suffice.
Y.
>
>
>
>
> --
> Richard Chan
>
>
> _______________________________________________
> Users mailing list
> Users(a)ovirt.org
> http://lists.ovirt.org/mailman/listinfo/users
>
>
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7:23 p.m.
On 12/07/2017 01:10 AM, Richard Chan wrote:
What is the best practice for iSCSI storage domains:
Many small targets vs a few large targets?
Specific example: if you wanted a 8TB storage domain would you prepare a
single 8TB LUN or (for example) 8 x 1 TB LUNs.
There's no "best" answer for this. However, if you know you're going to
be doing a ton of VMs (storage), then less is best. The problem with
"less" is that you might end up wasting more space for longer periods of
time. Not necessarily an issue for subsystems with thin provisioning,
but just something to be aware of.
The number of virtual disks can get extreme. And while that's not
really related to the iSCSI, just getting all those virtual disks online
(for example, after node maintenance) can get time consuming.
Took me over 30 minutes the other day.
Obviously that tends to get worse as the number of virtual disks increases.
So, there is something to be said about trying to reduce the number of
virtual disks.
Our standard for new storage domains is 6TB.
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4 comments
5 participants
participants (5)
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Christopher Cox -
FERNANDO FREDIANI -
Maor Lipchuk -
Richard Chan -
Yaniv Kaul