{"id":15768,"date":"2022-06-19T07:46:43","date_gmt":"2022-06-18T22:46:43","guid":{"rendered":"https:\/\/je1sgh.mydns.jp\/je1sghblog\/?p=15768"},"modified":"2022-06-19T07:46:43","modified_gmt":"2022-06-18T22:46:43","slug":"zram-3-%e3%80%9czram%e3%81%ae%e8%a9%b1%e3%81%a7%e3%81%af%e3%81%aa%e3%81%84%e3%80%9c","status":"publish","type":"post","link":"https:\/\/je1sgh.mydns.jp\/je1sghblog\/?p=15768","title":{"rendered":"zram (3) \u301czram\u306e\u8a71\u3067\u306f\u306a\u3044\u301c"},"content":{"rendered":"\n

zramをswapに使えば，SDカードで動かしているRaspberry Pi 4 Model B (RPi4) の挙動は少しは改善するかという試みですが，その答えはNOでした．遅さはswapだけの問題ではないです．<\/p>\n\n\n\n

で，それを検証するのに四苦八苦しました．これまでRPi4にLinux distroをインストールする場合，インストール用イメージをSDカードに焼いて1<\/a><\/sup>CD\/DVDはともかくSDカードも「焼く」で良いかの議論はめんどうなので割愛します．<\/span>起動して，必要最低限の設定を終えたら，SDカードの中身をSSDにコピーして，多少のおまじないをしてからSSDから起動するということでうまくいってきました．<\/p>\n\n\n\n

Raspberry Pi 3 Model B(+)の場合も，ルートディスクの中身をSSDにコピーしてSDカードのvfat内のcmdline.txtを書き換えてOKでした2<\/a><\/sup>この場合は，RPi4と違って，起動用のSDカードは必要です．なんかちょっと難しいまじないをすればSDカードが要らなくなるようですが，そこまでは追求しません😓<\/span>．<\/p>\n\n\n\n

当然，SSDで動いていれば，適切にその内容をSDカードにコピーすれば，SDカードのみで使える様になるはずです．それがなかなかうまくいきませんでした．<\/p>\n\n\n\n

SDカードは，Toshibaのmicro SDカード64GBです．<\/p>\n\n\n

\n
\"\"<\/figure>\n<\/div>\n\n\n

過程を思い出すのがめんどうなので，結果だけ書きますと，比較のために使用した1TBのHDDはもともとgptで成功．64GB SDカードはUSBアダプターを使ってテストして，dosではだめで，これもgptにしたら成功．成功したところで，RPi4のSDカードスロットに差しても起動するようになった，といったところでしょうか．<\/p>\n\n\n\n

なぜSDカードからの起動がdosパーティションではだめで，gptならうまくいくのかは調べません．64GBだからか，Toshiba製だからなのか，解りません．<\/p>\n\n\n\n

将来，また今回のことを忘れで試行錯誤する自分宛のメモですが，「cmdline.txtやfstabの記述は，UUIDを使うこと」，です．具体的なディバイス名は，複数のUSBディバイスを使う時や，RPi4本体のSDカードスロットに差し込む時に変わるからです．<\/p>\n\n\n\n

もうひとつ，SSD\/HDDからSDカードへのrsyncによるコピーは，一晩以上かかります．<\/p>\n","protected":false},"excerpt":{"rendered":"

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