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Cc: "user@cassandra.apache.org" <user@cassandra.apache.org>
From: Mohit Anchlia <mohitanchlia@gmail.com>
Subject: Re: Commit log on USB flash disk?
Date: Sat, 16 Nov 2013 11:14:13 -0800
To: "user@cassandra.apache.org" <user@cassandra.apache.org>


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In our testing USB tends to be slower. If there is something more integrated=
 internally would give you better performance

Sent from my iPhone

On Nov 16, 2013, at 8:30 AM, Dan Simpson <dan.simpson@gmail.com> wrote:

> It doesn't seem like a great idea.  The USB drives typically use dynamic w=
ear leveling.  See this analysis on wear: https://www.google.com/url?sa=3Dt&=
rct=3Dj&q=3D&esrc=3Ds&source=3Dweb&cd=3D3&ved=3D0CD8QFjAC&url=3Dhttp%3A%2F%2=
Fwww.usenix.org%2Fevent%2Ffast10%2Ftech%2Ffull_papers%2Fboboila.pdf&ei=3DqZy=
HUrizFtKAygGs9YGoCg&usg=3DAFQjCNHTC7d6fcI1CNWmjbHMwgXI1nUWcQ&sig2=3DBaWgHj3i=
b-cQOBPQsoCadA&bvm=3Dbv.56643336,d.aWc&cad=3Drjt
>=20
> If you you do end up using it, make sure to monitor write latency so you d=
on't get hit by the bus.
>=20
>=20
> On Sat, Nov 16, 2013 at 6:12 AM, David Tinker <david.tinker@gmail.com> wro=
te:
>> Our hosting provider has a cost effective server with 2 x 4TB disks
>> with a 16G (or 64G) USB thumb drive option. Would it make sense to put
>> the Cassandra commit log on the USB thumb disk and use RAID0 to use
>> both 4TB disks for data (and Ubuntu 12.04)?
>>=20
>> Anyone know how long USB flash disks last when use for a write heavy
>> workload like this?
>>=20
>> Please tell me if this is a really bad idea.
>>=20
>> Our alternative is to use one 4TB disk for commit log and one for
>> data. Of course this will give us only half the space.
>>=20
>> Thanks
>> David
>=20

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<html><head><meta http-equiv=3D"content-type" content=3D"text/html; charset=3D=
utf-8"></head><body dir=3D"auto"><div>In our testing USB tends to be slower.=
 If there is something more integrated internally would give you better perf=
ormance<br><br>Sent from my iPhone</div><div><br>On Nov 16, 2013, at 8:30 AM=
, Dan Simpson &lt;<a href=3D"mailto:dan.simpson@gmail.com">dan.simpson@gmail=
.com</a>&gt; wrote:<br><br></div><blockquote type=3D"cite"><div><div dir=3D"=
ltr">It doesn't seem like a great idea. &nbsp;The USB drives typically use d=
ynamic wear leveling. &nbsp;See this analysis on wear: <a href=3D"https://ww=
w.google.com/url?sa=3Dt&amp;rct=3Dj&amp;q=3D&amp;esrc=3Ds&amp;source=3Dweb&a=
mp;cd=3D3&amp;ved=3D0CD8QFjAC&amp;url=3Dhttp%3A%2F%2Fwww.usenix.org%2Fevent%=
2Ffast10%2Ftech%2Ffull_papers%2Fboboila.pdf&amp;ei=3DqZyHUrizFtKAygGs9YGoCg&=
amp;usg=3DAFQjCNHTC7d6fcI1CNWmjbHMwgXI1nUWcQ&amp;sig2=3DBaWgHj3ib-cQOBPQsoCa=
dA&amp;bvm=3Dbv.56643336,d.aWc&amp;cad=3Drjt">https://www.google.com/url?sa=3D=
t&amp;rct=3Dj&amp;q=3D&amp;esrc=3Ds&amp;source=3Dweb&amp;cd=3D3&amp;ved=3D0C=
D8QFjAC&amp;url=3Dhttp%3A%2F%2Fwww.usenix.org%2Fevent%2Ffast10%2Ftech%2Ffull=
_papers%2Fboboila.pdf&amp;ei=3DqZyHUrizFtKAygGs9YGoCg&amp;usg=3DAFQjCNHTC7d6=
fcI1CNWmjbHMwgXI1nUWcQ&amp;sig2=3DBaWgHj3ib-cQOBPQsoCadA&amp;bvm=3Dbv.566433=
36,d.aWc&amp;cad=3Drjt</a><div>
<br></div><div>If you you do end up using it, make sure to monitor write lat=
ency so you don't get hit by the bus.</div></div><div class=3D"gmail_extra">=
<br><br><div class=3D"gmail_quote">On Sat, Nov 16, 2013 at 6:12 AM, David Ti=
nker <span dir=3D"ltr">&lt;<a href=3D"mailto:david.tinker@gmail.com" target=3D=
"_blank">david.tinker@gmail.com</a>&gt;</span> wrote:<br>
<blockquote class=3D"gmail_quote" style=3D"margin:0 0 0 .8ex;border-left:1px=
 #ccc solid;padding-left:1ex">Our hosting provider has a cost effective serv=
er with 2 x 4TB disks<br>
with a 16G (or 64G) USB thumb drive option. Would it make sense to put<br>
the Cassandra commit log on the USB thumb disk and use RAID0 to use<br>
both 4TB disks for data (and Ubuntu 12.04)?<br>
<br>
Anyone know how long USB flash disks last when use for a write heavy<br>
workload like this?<br>
<br>
Please tell me if this is a really bad idea.<br>
<br>
Our alternative is to use one 4TB disk for commit log and one for<br>
data. Of course this will give us only half the space.<br>
<br>
Thanks<br>
<span class=3D"HOEnZb"><font color=3D"#888888">David<br>
</font></span></blockquote></div><br></div>
</div></blockquote></body></html>=

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