From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from lists.gentoo.org (pigeon.gentoo.org [208.92.234.80]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits)) (No client certificate requested) by finch.gentoo.org (Postfix) with ESMTPS id A380B158042 for ; Thu, 14 Nov 2024 17:00:17 +0000 (UTC) Received: from pigeon.gentoo.org (localhost [127.0.0.1]) by pigeon.gentoo.org (Postfix) with SMTP id 603B9E087B; Thu, 14 Nov 2024 17:00:12 +0000 (UTC) Received: from mail-yw1-x112f.google.com (mail-yw1-x112f.google.com [IPv6:2607:f8b0:4864:20::112f]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by pigeon.gentoo.org (Postfix) with ESMTPS id C5A5DE0837 for ; Thu, 14 Nov 2024 17:00:11 +0000 (UTC) Received: by mail-yw1-x112f.google.com with SMTP id 00721157ae682-6ea053b5929so8374717b3.0 for ; Thu, 14 Nov 2024 09:00:11 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1731603611; x=1732208411; darn=lists.gentoo.org; h=in-reply-to:mime-version:user-agent:date:message-id:autocrypt:from :references:to:subject:from:to:cc:subject:date:message-id:reply-to; bh=3g+G5zEchGqUBi+qbZJxpzMUX48rFxfrWpmOduYfC1A=; b=FzZz2CRD8Ce9TgsV+PGu3toRdn5XZysw5dBTCmFjmVSgVSpjscZs6QhAbuaYJjAZzE tX74TWLXjGOH1iHRejUksHZPmWOq5oEaDXO4om48SpyapEbnWQny0h3ZERlVm0PhhbR3 nyd0mqptQPr9dWbYy04clrukOkmxRiCWB/a1jqb66wEwSqvj11nFSbXYoreN0S5d2BFR n3Dn9iPtq60+feS7j/jytxRd1FH37H91aWt5Lpo7P92yI9GqkTnUw9fxb5p9VkqvAOwc YnoXZVx7Tra+js6szPCjJ1GUb1HTF2fvBEDjm1w7UKXxtNDRMe2Yls8RAMw0lNAMTvUz xs9Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1731603611; x=1732208411; h=in-reply-to:mime-version:user-agent:date:message-id:autocrypt:from :references:to:subject:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=3g+G5zEchGqUBi+qbZJxpzMUX48rFxfrWpmOduYfC1A=; b=GWmjvw5AFsVOwI1efx4FUsZoLwdkuwZ6Xi5X98N4kJoWAksj9DEbW0OpxphlpeAH+P d9jgK31QPOEzrUQ/ARU/LozsuX++Ug/+6mRvl8ymhsMAQ31PBXqfbcn7lorxGEPYg+xi c2DKHAd0pEIToJdsPGr5s293KDPgCj35Q8PC2v/nJXr83XZVeDXX1WyKgAoS0V223HqF eWMrLPIiZZLAsdmQq7uqBUfVB/vP3Iz72dXdU7gaz8I9YDjSIl9o1jZ8RAJbwgJxiZqG JtdJCvPi4YJpyT0274niTEuxrl2thxuv6tNr4WE90IXdd91zdi0XarCTOdDAiIXyz0f7 46ig== X-Gm-Message-State: AOJu0YyuaZS+U121Ubt/rBfFICTHdJmdE5fgybN/Txs6fohCK8YSak1P o6jNH9g+5TDligDNroG1GsAO4+ftHoJETXYTFURT68DbBFFqpZmsFZLiRg== X-Google-Smtp-Source: AGHT+IEdvNIyNatk93V4x/pNntsPx+DReKrCMxRIQnVln2GHlkNo8CKRECTPdgHCivqPq0L1g39p9w== X-Received: by 2002:a05:690c:64c6:b0:6e2:12e5:35b4 with SMTP id 00721157ae682-6ee42f44a64mr34878777b3.0.1731603610817; Thu, 14 Nov 2024 09:00:10 -0800 (PST) Received: from [10.8.8.10] ([92.119.19.11]) by smtp.gmail.com with ESMTPSA id 00721157ae682-6ee44046effsm3188117b3.51.2024.11.14.09.00.08 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 14 Nov 2024 09:00:09 -0800 (PST) Subject: Re: [gentoo-user] Seagate hard drives with dual actuators. To: gentoo-user@lists.gentoo.org References: <1879585.atdPhlSkOF@rogueboard> From: Dale Autocrypt: addr=rdalek1967@gmail.com; prefer-encrypt=mutual; keydata= mQINBGFSciYBEADcEGMyJBSuavKO/XKUVvgkxck7Nl8Iuu8N2lcnRji/rSKg5c1Acix1ll9i oW8JBCHwvn0+Xy60BvEsqcup3YSHw5STl/bR1ePEehtnYrg8FdjdS91+B805RfnKMm69rFVI wLSBHQrSG1yxHd8CloWoEdhmVtP24buajbh114bgXd9ahtpZrCVMrWdWYUg2mEXguGV5uNAh Rf8SWxDNc79w24JxsV34a8niMUYMjzWr0rafIbzk732X38vGjVMLo/2mMpkbp9mPp++LHoY+ 0Pet8zxxdXPJSCd475kza1AD+hhSyBZXB9yknYWgyY3cZe1rGmooJSi2KX4QxO7npwLThcO1 be6KKRkd35+Fi/a1BzVOHsZMiK/gcwxEFoMd27gir4ehaeHJfFXl+65w4hj0EsOZSxrJrm2C R50g5By2czSKP1bADEygFNpIJj51AR+wM88NImG2RPtlT2maYBzazvF05g65cdHXGp1C7W5P wwwKU2DgABB2t7N7z5A69LnryBRw4zUYDRRYLTYlBlYgg+xILm2c0OrBdxJgLJa7JE50Eo25 d3PFwt9J0gYvqy6sPFLl9So0sDg9zm0hKQtXOP5kgropUFGrNoJI+mjwF4rYLRBVzZwNAvlO OhEvHubBo3mEllv4x+FeptwXZxlk7gUsdqI8AxnFB8K9wi6FVQARAQABtBtEYWxlIDxyZGFs ZWsxOTY3QGdtYWlsLmNvbT6JAk4EEwEIADgCGyMFCwkIBwIGFQoJCAsCBBYCAwECHgECF4AW IQQSG1h01ruv/WNXc3Q3RqOgiQH1GwUCYVJy8gAKCRA3RqOgiQH1G+waEACeTZCt77jnRAmQ AV7otKuZekDWiLi3Eig8tj5ZJiCNSYA/hIxzmexRP0GMqjitcXK1iGwWcvMzzvIq30GAjIfB 4BR38cnXbtBa6fNewiT7QaZe/Hn6yBRldXNQypzbHy+/o27bUEy+oX4rE7etUgEHQAjuw7xz XFWg4tH1/KJvsOVY5upnWc5LdxYhsuQ3dQD4b22GsK0pOBDfb9PiirYM8eGKvrVuq4E/c75z lDDFhINl18lNZ9D0ZFL3IkTjHsAAqFH9uhnnEB8CWdHbBewPEfRaOhBUYWZ3Q8uTkmDgZT8q D9jlvLEdw7Nh2ApdxoepnI/4D+ql2Gr4DtH7SEPydr5gcf1Qr/2bXRb1hAYnIVcbncs/Bm3Z bkRKPVWMfE3Fusa+p5hMzixk0YysMaTHlc7mYRYAEZGnPMXnmcCbetwARU7A0yz1M1kCMOAQ Lsz8KH5kv3cRenMB6SFfjND2JfAK61H5TtnPq3L8noS2ZykRYxq9Nm3X64O1tJojIKBoZFr8 AwYNCvqC6puUyGMuzHPh7jPof8glfrrEKIYUvNPGMDoVX3IGetxh/9l6NcxgFA4JGoR+LS3C zmeNrwlllAe3OEUfKoWVQ+pagpSdM+8hHolaSda4Ys66Z3fCR4ZvcTqfhTAVskpqdXa4isAk 7vTcXu3L499ttywEp7rJTbkCDQRhUnImARAAncUdVhmtRr59zqpTUppKroQYlzR0jv8oa7DG K4gakTAT2N7evnI9wpssmzyVk8VEiLzhnFQ/Ol3FRt6hZCXDJt0clyHOyTfvz/MNFttWuZTc mLpSvmRR6VRjAH+Tz3Eam2xUw3PGuH97BcXQ3NnX3msv1UDxtxxBu6e2YrdeOhrCUSgzokcJ 98ChUNy934cgepPybAI12lSWqVFQ1aG7jExZfiUk+333fPSDbpKoZbTW5YJLXbycmW/C1IWL qYQyNjRWKaGoJtUWFhhmNiOQct7n90aKivNVPavmN+UQ9LlMaINtf9T6XCzLfogCFsulDCDJ 0yNQLDTurHaB4E71xoctgXmLLq9z1RQ0W2XiVAAOZQj6K3+d0AOUjDhCQ2QW8dUSq0ckkZXV DKVJOGS8Nhf2eIWIqRnP3AcUiiaiFGqUaVUmUAZ6h/oJmgghEu/1S+pcuUKU5i69+XCZ3hH2 Jzwzbf7K+FAIkOhCfHncF8i1N1pk00pOVykNnqHTfFo3qFusHt0ZWgXVnnn4pYdXqZNoDhvF BRE5Vm4k/k96Pw8HRx6Os6eFSRrlqGzRgqsu86FekxusXB9UGv4lJhtU/J+8MRWsh22K718s DbQnABicGKFz1qQlWvcf59oTByhLINJCBt1WXl+TzJDXepr3QSkqmK41dO9Hob97C9dMiK8A EQEAAYkCNgQYAQgAIAIbDBYhBBIbWHTWu6/9Y1dzdDdGo6CJAfUbBQJhUnLyAAoJEDdGo6CJ AfUbVHIQAKSWw620vPhR3A/njU2z77F3z/Jk+HTKdE3fIyWSWdkYN7CBFL0NguOMP30WZ+qE sJhZu7T5hf251MwQUUt27xlfnKYOmQs7CqONlXuXlGZI6WufrUjxNcVz+5gJsqvUWuuJWsgg sDmE92IBnfG/f81fPHWQyfr/SF4wYDMyoFp5xCCQpp1zB63iuFvvrhxBkEHzmbRtVDOhl0Xp BVEDR1w3QRACw9QJD/KM05Czv9JNQYlwinWO/OaQ9cMlUpKLgswUPg9IZ5vucxScfuAUA5uC B1jlAQ8ZPlVukBmbEv5RGOv+lpuEbA3YDMVtEeH4YMFbjt/+vH3Cr2vTbp5JlpByLburJEH0 WXZLUawEfUsZvVwpOuJK75vaa2HYXee+Cb3iCIzwfIfctdlqzUcbGRczlRNM59hpvj4z29Gh 3kAxVHItAYq54ikxQ9l4hQ8s9sLYPbX/WtcBxNX8crBSw0FLnmzGleVEtBHyqtt5CLzQNgrj GYWl1vKDUmRPw1CdZ1c+fMN9CY11jOM5B5ZnqZWfDeVYO2iJ5SuvTycChexCb8WYn1bdCBIo bBtga2RBXbVt4Mh9E4owsszefn51MwfjXxB20Fc5k3GU1AVpTCMs3ayYCzo0b2pvEvdjtDcA CYLEFPWgaFX9iQAM/CDfKvTtvgGWpqtCL2raq/mQoJEU Message-ID: Date: Thu, 14 Nov 2024 11:00:07 -0600 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Firefox/91.0 SeaMonkey/2.53.19 Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-Id: Gentoo Linux mail X-BeenThere: gentoo-user@lists.gentoo.org Reply-to: gentoo-user@lists.gentoo.org X-Auto-Response-Suppress: DR, RN, NRN, OOF, AutoReply MIME-Version: 1.0 In-Reply-To: <1879585.atdPhlSkOF@rogueboard> Content-Type: multipart/alternative; boundary="------------1DE718866EB03BA09D6749DB" X-Archives-Salt: f61fce50-bad9-47d6-9382-1acf1b611806 X-Archives-Hash: 5adb611c015a394ca4dcb3e901ff956f This is a multi-part message in MIME format. --------------1DE718866EB03BA09D6749DB Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Michael wrote: > On Wednesday 13 November 2024 23:10:10 GMT Dale wrote: >> Howdy, >> >> One of my PVs is about 83% full. Time to add more space, soon anyway. >> I try not to go past 90%. Anyway, I was looking at hard drives and >> noticed something new. I think I saw one a while back but didn't look >> into it at the time. I'm looking at 18TB drives, right now. Some new >> Seagate drives have dual actuators. Basically, they have two sets of >> heads. In theory, if circumstances are right, it could read data twice >> as fast. Of course, most of the time that won't be the case but it can >> happen often enough to make it get data a little faster. Even a 25% or >> 30% increase gives Seagate something to brag about. Another sales tool. >> Some heavy data users wouldn't mind either. >> >> My question is this. Given they cost about $20 more, from what I've >> found anyway, is it worth it? Is there a downside to this new set of >> heads being added? I'm thinking a higher failure rate, more risk to >> data or something like that. I think this is a fairly new thing, last >> couple years or so maybe. We all know how some new things don't work out. >> >> Just looking for thoughts and opinions, facts if someone has some. >> Failure rate compared to single actuator drives if there is such data. >> My searched didn't help me find anything useful. >> >> Thanks. >> >> Dale >> >> :-) :-) > I don't know much about these drives beyond what the OEM claims. From what I > read, I can surmise the following hypotheses: > > These drives draw more power from your PSU and although they are filled with > helium to mitigate against higher power/heat, they will require better cooling > at the margin than a conventional drive. > > Your system will use dev-libs/libaio to read the whole disk as a single SATA > drive (a SAS port will read it as two separate LUNs). The first 50% of LBAs > will be accessed by the first head and the last 50% by the other head. So > far, so good. > > Theoretically, I suspect this creates a higher probability of failure. In the > hypothetical scenario of a large sequential write where both heads are writing > data of a single file, then both heads must succeed in their write operation. > The cumulative probability of success of head A + head B is calculated as > P(A⋂B). As an example, if say the probability of a successful write of each > head is 80%, the cumulative probability of both heads succeeding is only 64%: > > 0.8 * 0.8 = 0.64 > > As long as I didn't make any glaring errors, this simplistic thought > experiment assumes all else being equal with a conventional single head drive, > but it never is. The reliability of a conventional non-helium filled drive > may be lower to start with. Seagate claim their Exos 2 reliability is > comparable to other enterprise-grade hard drives, but I don't have any real > world experience to share here. I expect by the time enough reliability > statistics are available, the OEMs would have moved on to different drive > technologies. > > When considering buying this drive you could look at the market segment needs > and use cases Seagate/WD could have tried to address by developing and > marketing this technology. These drives are for cloud storage > implementations, where higher IOPS, data density and speed of read/write is > desired, while everything is RAID'ed and backed up. The trade off is power > usage and heat. > > Personally, I tend to buy n-1 versions of storage solutions, for the following > reasons: > > 1. Price per GB is cheaper. > 2. Any bad news and rumours about novel failing technologies or unsuitable > implementations (e.g. unmarked SMRs being used in NAS) tend to spread far and > wide over time. > 3. High volume sellers start offering discounts for older models. > > However, I don't have a need to store the amount of data you do. Most of my > drives stay empty. Here's a 4TB spinning disk with 3 OS and 9 partitions: > > ~ # gdisk -l /dev/sda | grep TiB > Disk /dev/sda: 7814037168 sectors, 3.6 TiB > Total free space is 6986885052 sectors (3.3 TiB) > > HTH Sounds like my system may not can even handle one of these.  I'm not sure my SATA ports support that stuff.  It sounds like this is not something I really need anyway.  After all, I'm already spanning my data over three drives.  I'm sure some data is coming from each drive.  No way to really know for sure but makes sense.  Do you have a link or something to a place that explains what parts of the Seagate model number means?  I know ST is for Seagate.  The size is next.  After that, everything I find is old and outdated.  I looked on the Seagate website to but had no luck.  I figure someone made one, somewhere.  A link would be fine. Thanks. Dale :-)  :-)  --------------1DE718866EB03BA09D6749DB Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: 8bit
Michael wrote:
On Wednesday 13 November 2024 23:10:10 GMT Dale wrote:

Howdy,

One of my PVs is about 83% full.  Time to add more space, soon anyway.
I try not to go past 90%.  Anyway, I was looking at hard drives and
noticed something new.  I think I saw one a while back but didn't look
into it at the time.  I'm looking at 18TB drives, right now.  Some new
Seagate drives have dual actuators.  Basically, they have two sets of
heads.  In theory, if circumstances are right, it could read data twice
as fast.  Of course, most of the time that won't be the case but it can
happen often enough to make it get data a little faster.  Even a 25% or
30% increase gives Seagate something to brag about.  Another sales tool.
 Some heavy data users wouldn't mind either.

My question is this.  Given they cost about $20 more, from what I've
found anyway, is it worth it?  Is there a downside to this new set of
heads being added?  I'm thinking a higher failure rate, more risk to
data or something like that.  I think this is a fairly new thing, last
couple years or so maybe.  We all know how some new things don't work out.

Just looking for thoughts and opinions, facts if someone has some.
Failure rate compared to single actuator drives if there is such data.
My searched didn't help me find anything useful.

Thanks.

Dale

:-)  :-)

I don't know much about these drives beyond what the OEM claims.  From what I 
read, I can surmise the following hypotheses:

These drives draw more power from your PSU and although they are filled with 
helium to mitigate against higher power/heat, they will require better cooling 
at the margin than a conventional drive.

Your system will use dev-libs/libaio to read the whole disk as a single SATA 
drive (a SAS port will read it as two separate LUNs).  The first 50% of LBAs 
will be accessed by the first head and the last 50% by the other head.  So 
far, so good.

Theoretically, I suspect this creates a higher probability of failure.  In the 
hypothetical scenario of a large sequential write where both heads are writing 
data of a single file, then both heads must succeed in their write operation.  
The cumulative probability of success of head A + head B is calculated as 
P(A⋂B).  As an example, if say the probability of a successful write of each 
head is 80%, the cumulative probability of both heads succeeding is only 64%:

0.8 * 0.8 = 0.64

As long as I didn't make any glaring errors, this simplistic thought 
experiment assumes all else being equal with a conventional single head drive, 
but it never is.  The reliability of a conventional non-helium filled drive 
may be lower to start with.  Seagate claim their Exos 2 reliability is 
comparable to other enterprise-grade hard drives, but I don't have any real 
world experience to share here.  I expect by the time enough reliability 
statistics are available, the OEMs would have moved on to different drive 
technologies.

When considering buying this drive you could look at the market segment needs 
and use cases Seagate/WD could have tried to address by developing and 
marketing this technology.  These drives are for cloud storage 
implementations, where higher IOPS, data density and speed of read/write is 
desired, while everything is RAID'ed and backed up.  The trade off is power 
usage and heat.

Personally, I tend to buy n-1 versions of storage solutions, for the following 
reasons:

1. Price per GB is cheaper.
2. Any bad news and rumours about novel failing technologies or unsuitable 
implementations (e.g. unmarked SMRs being used in NAS) tend to spread far and 
wide over time.
3. High volume sellers start offering discounts for older models.

However, I don't have a need to store the amount of data you do.  Most of my 
drives stay empty.  Here's a 4TB spinning disk with 3 OS and 9 partitions:

~ # gdisk -l /dev/sda | grep TiB
Disk /dev/sda: 7814037168 sectors, 3.6 TiB
Total free space is 6986885052 sectors (3.3 TiB)

HTH

Sounds like my system may not can even handle one of these.  I'm not sure my SATA ports support that stuff.  It sounds like this is not something I really need anyway.  After all, I'm already spanning my data over three drives.  I'm sure some data is coming from each drive.  No way to really know for sure but makes sense. 

Do you have a link or something to a place that explains what parts of the Seagate model number means?  I know ST is for Seagate.  The size is next.  After that, everything I find is old and outdated.  I looked on the Seagate website to but had no luck.  I figure someone made one, somewhere.  A link would be fine.

Thanks.

Dale

:-)  :-) 
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